Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface int...Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components.According to their hardness,brittle materials can be roughly divided into hard-brittle and soft-brittle.Although there have been some literature reviews for ultraprecision machining of hard-brittle materials,up to date,very few review papers are available that focus on the processing of soft-brittle materials.Due to the‘soft’and‘brittle’properties,this group of materials has unique machining characteristics.This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials.Critical aspects of machining mechanisms,such as chip formation,surface topography,and subsurface damage for different machining methods,including diamond turning,micro end milling,ultraprecision grinding,and micro/nano burnishing,are compared in terms of tool-workpiece interaction.The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed,and dominating factors are sorted out.Problems and challenges in the engineering applications are identified,and solutions/guidelines for future R&D are provided.展开更多
In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,position...In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are stable.In ultraprecision machining of freeform surfaces using slow tool servo mode in particular,however,account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece positioning.The important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application scenario.In this paper,an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo mode.The approach is focused on seamless integration of multibody dynamics,cutting forces,and machining dynamics,while targeting the positioning and control of the tool–workpiece loop in the machining system.The positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece surface.The interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining systems.The approach is illustrated using a virtual machining system developed and supported with simulations and experimental trials.Furthermore,the paper provides further explorations and discussion on implementation perspectives of the approach,in combination with case studies,as well as discussing its fundamental and industrial implications.展开更多
A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have ...A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have been considered, and the size effect is accountable forthe new model. It is desired that the model can be well applicable to conventional diamond turningand the model may be employed as a tool in the design of diamond tools. This approach is quitedifferent from traditional investigations primarily based on empirical studies. As the depth of cutbecomes the same order as the rounded cutting edge radius, sliding along the clearance face due toelastic recovery of workpiece material and plowing due to the rounded cutting edge may becomeimportant in micro-machining, the forces acting on the cutting edge rounding and the clearance facecan not be neglected. For this reason, it is very important to understand the influence of someparameters on tool forces and develop a model of the relationship between them.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
文摘Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components.According to their hardness,brittle materials can be roughly divided into hard-brittle and soft-brittle.Although there have been some literature reviews for ultraprecision machining of hard-brittle materials,up to date,very few review papers are available that focus on the processing of soft-brittle materials.Due to the‘soft’and‘brittle’properties,this group of materials has unique machining characteristics.This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials.Critical aspects of machining mechanisms,such as chip formation,surface topography,and subsurface damage for different machining methods,including diamond turning,micro end milling,ultraprecision grinding,and micro/nano burnishing,are compared in terms of tool-workpiece interaction.The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed,and dominating factors are sorted out.Problems and challenges in the engineering applications are identified,and solutions/guidelines for future R&D are provided.
基金The authors are grateful for Ph.D.Scholarship funding support from Brunel University London and the UKEPSRC.
文摘In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are stable.In ultraprecision machining of freeform surfaces using slow tool servo mode in particular,however,account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece positioning.The important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application scenario.In this paper,an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo mode.The approach is focused on seamless integration of multibody dynamics,cutting forces,and machining dynamics,while targeting the positioning and control of the tool–workpiece loop in the machining system.The positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece surface.The interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining systems.The approach is illustrated using a virtual machining system developed and supported with simulations and experimental trials.Furthermore,the paper provides further explorations and discussion on implementation perspectives of the approach,in combination with case studies,as well as discussing its fundamental and industrial implications.
基金This project is supported by National Natural Science Foundation of China (No.50175022)National Aerospace Support Foundation of China(No.0223HIT07).
文摘A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have been considered, and the size effect is accountable forthe new model. It is desired that the model can be well applicable to conventional diamond turningand the model may be employed as a tool in the design of diamond tools. This approach is quitedifferent from traditional investigations primarily based on empirical studies. As the depth of cutbecomes the same order as the rounded cutting edge radius, sliding along the clearance face due toelastic recovery of workpiece material and plowing due to the rounded cutting edge may becomeimportant in micro-machining, the forces acting on the cutting edge rounding and the clearance facecan not be neglected. For this reason, it is very important to understand the influence of someparameters on tool forces and develop a model of the relationship between them.
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.
