The dynamic performance and the stability are essential for a system. A new circuit topology used for electrical discharge machining (EDM) power and made up of complex-pulse (voltage-pulse and current-pulse) is presen...The dynamic performance and the stability are essential for a system. A new circuit topology used for electrical discharge machining (EDM) power and made up of complex-pulse (voltage-pulse and current-pulse) is presented. The large-signal model of it is also derived. Based on the comprehensive analysis of the system model, the compensator is designed to make the system match better and to improve its dynamic performance and the stability under perturbations. Finally, the design methods and the analysis are verified by simulation and experimental results.展开更多
A Micro Electrical Discharge Machining (MEDM) equipment was developed in this paper,on which the CNC interpolation for 3-axis linkage movement could be realized easily. By this micro-EDM equipment,the fabrication proc...A Micro Electrical Discharge Machining (MEDM) equipment was developed in this paper,on which the CNC interpolation for 3-axis linkage movement could be realized easily. By this micro-EDM equipment,the fabrication process of microelectrode,micro hole,silicon wafer and complex microstructure was discussed. The process rules of machining efficiency and the relative electrode wear rate as well as the machining mechanism and performance of silicon micro-EDM were also researched. Machining experiments showed that the microelectrode diameter as small as 6 μm and the micro hole with minimum size of 10 μm could be obtained steadily,and the maximum aspect ratios of microelectrode and micro hole were over 25 and 10 respectively. And silicon micro-EDM experiments showed that the micro beam with the aspect ratios over 15 could be obtained easily. And a micro beam with minimum size of 23 μm width on a silicon wafer with 420 μm thickness was achieved. At last,the microstructure machining technology for micro-EDM was also discussed. And a micro-facial sculpture with free space curved surface and size of 1 mm×0.3 mm×0.18 mm was also machined successfully.展开更多
The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
Compared to conventional quantum dot light-emitting diodes,tandem quantum dot light-emitting diodes(TQLEDs)possess higher device efficiency and more applications in the field of flat panel display and solid-state ligh...Compared to conventional quantum dot light-emitting diodes,tandem quantum dot light-emitting diodes(TQLEDs)possess higher device efficiency and more applications in the field of flat panel display and solid-state lighting in the future.The TQLED is a multilayer structure device which connects two or more light-emitting units by using an interconnection layer(ICL),which plays an extremely important role in the TQLED.Therefore,realizing an effective ICL is the key to obtain high-efficiency TQLEDs.In this work,the p-type materials polys(3,4-ethylenedioxythiophene),poly(styrenesulfonate)(PEDOT:PSS)and the n-type material zinc magnesium oxide(ZnMgO),were used,and an effective hybrid ICL,the PEDOT:PSS-GO/ZnMgO,was obtained by doping graphene oxide(GO)into PEDOT:PSS.The effect of GO additive on the ICL was systematically investigated.It exhibits that the GO additive brought the fine charge carrier generation and injection capacity simultaneously.Thus,the all solutionprocessed red TQLEDs were prepared and characterized for the first time.The maximum luminance of 40877 cd/m^(2) and the highest current efficiency of 19.6 cd/A were achieved,respectively,showing a 21%growth and a 51%increase when compared with those of the reference device without GO.The encouraging results suggest that our investigation paves the way for efficient all solution-processed TQLEDs.展开更多
To meet the demands for highly advanced components with ultra precise contour accuracy and optical surface quality arising in the fields of photonics and optics, automotive, medical applications and biotechnology, con...To meet the demands for highly advanced components with ultra precise contour accuracy and optical surface quality arising in the fields of photonics and optics, automotive, medical applications and biotechnology, consumer electronics and renewable energy, more advanced production machines and processes have to be developed. As the complexity of machine tools rises steadily, the automation of manufacture increases rapidly, processes become more integrated and cycle times have to be reduced significantly, challenges of engineering efficient machine tools with respect to these demands expand every day. Especially the manufacture of freeform geometries with non-continuous and asymmetric surfaces requires advanced diamond machining strategies involving highly dynamic axes movements with a high bandwidth and position accuracy. Ultra precision lathes additionally equipped with Slow Tool and Fast Tool systems can be regarded as state-of-the-art machines achieving the objectives of high quality optical components. The mechanical design of such ultra precision machine tools as well as the mechanical integration of additional highly dynamic axes are very well understood today. In contrast to that, neither advanced control strategies for ultra precision machining nor the control integration of additional Fast Tool systems have been sufficiently developed yet. Considering a complex machine setup as a mechatronic system, it becomes obvious that enhancements to further increase the achievable form accuracy and surface quality and at the same time decrease cycle times and error sensitivity can only be accomplished by innovative, integrated control systems. At the Fraunhofer Institute for Production Technology IPT a novel, fully integrated control approach has been developed to overcome the drawbacks of state-of-the-art machine controls for ultra precision processes. Current control systems are often realized as decentralized solutions consisting of various computational hardware components for setpoint generation, machine control, HMI （human machine interface）, Slow Tool control and Fast Tool control. While implementing such a distributed control strategy, many disadvantages arise in terms of complex communication interfaces, discontinuous safety structures, synchronization of cycle times and the machining accuracy as a whole. The novel control approach has been developed as a fully integrated machine control including standard CNC （computer numerical control） and PLC （programmable logic controller） functionality, advanced setpoint generation methods, an extended HMI as well as an FPGA （field programmable gate array）-based controller for a voice coil driven Slow Tool and a piezo driven Fast Tool axis. As the new control system has been implemented as a fully integrated platform using digital communication via EtherCAT, a continuous safety strategy could be realized, the error sensitivity and EMC susceptibility could be significantly decreased and the overall process accuracy from setpoint generation over path interpolation to axes movements could be enhanced. The novel control at the same time offers additional possibilities of automation, process integration, online data acquisition and evaluation as well as error compensation methods.展开更多
文摘The dynamic performance and the stability are essential for a system. A new circuit topology used for electrical discharge machining (EDM) power and made up of complex-pulse (voltage-pulse and current-pulse) is presented. The large-signal model of it is also derived. Based on the comprehensive analysis of the system model, the compensator is designed to make the system match better and to improve its dynamic performance and the stability under perturbations. Finally, the design methods and the analysis are verified by simulation and experimental results.
文摘A Micro Electrical Discharge Machining (MEDM) equipment was developed in this paper,on which the CNC interpolation for 3-axis linkage movement could be realized easily. By this micro-EDM equipment,the fabrication process of microelectrode,micro hole,silicon wafer and complex microstructure was discussed. The process rules of machining efficiency and the relative electrode wear rate as well as the machining mechanism and performance of silicon micro-EDM were also researched. Machining experiments showed that the microelectrode diameter as small as 6 μm and the micro hole with minimum size of 10 μm could be obtained steadily,and the maximum aspect ratios of microelectrode and micro hole were over 25 and 10 respectively. And silicon micro-EDM experiments showed that the micro beam with the aspect ratios over 15 could be obtained easily. And a micro beam with minimum size of 23 μm width on a silicon wafer with 420 μm thickness was achieved. At last,the microstructure machining technology for micro-EDM was also discussed. And a micro-facial sculpture with free space curved surface and size of 1 mm×0.3 mm×0.18 mm was also machined successfully.
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
基金Project(11904298)supported by the National Natural Science Foundation of ChinaProject(cstc2020jcyj-msxm X0586)supported by Chongqing Natural Science Foundation,ChinaProject(S202010635001)supported by Chongqing Municipal Training Program of Innovation and Entrepreneurship for Undergraduates,China。
文摘Compared to conventional quantum dot light-emitting diodes,tandem quantum dot light-emitting diodes(TQLEDs)possess higher device efficiency and more applications in the field of flat panel display and solid-state lighting in the future.The TQLED is a multilayer structure device which connects two or more light-emitting units by using an interconnection layer(ICL),which plays an extremely important role in the TQLED.Therefore,realizing an effective ICL is the key to obtain high-efficiency TQLEDs.In this work,the p-type materials polys(3,4-ethylenedioxythiophene),poly(styrenesulfonate)(PEDOT:PSS)and the n-type material zinc magnesium oxide(ZnMgO),were used,and an effective hybrid ICL,the PEDOT:PSS-GO/ZnMgO,was obtained by doping graphene oxide(GO)into PEDOT:PSS.The effect of GO additive on the ICL was systematically investigated.It exhibits that the GO additive brought the fine charge carrier generation and injection capacity simultaneously.Thus,the all solutionprocessed red TQLEDs were prepared and characterized for the first time.The maximum luminance of 40877 cd/m^(2) and the highest current efficiency of 19.6 cd/A were achieved,respectively,showing a 21%growth and a 51%increase when compared with those of the reference device without GO.The encouraging results suggest that our investigation paves the way for efficient all solution-processed TQLEDs.
文摘To meet the demands for highly advanced components with ultra precise contour accuracy and optical surface quality arising in the fields of photonics and optics, automotive, medical applications and biotechnology, consumer electronics and renewable energy, more advanced production machines and processes have to be developed. As the complexity of machine tools rises steadily, the automation of manufacture increases rapidly, processes become more integrated and cycle times have to be reduced significantly, challenges of engineering efficient machine tools with respect to these demands expand every day. Especially the manufacture of freeform geometries with non-continuous and asymmetric surfaces requires advanced diamond machining strategies involving highly dynamic axes movements with a high bandwidth and position accuracy. Ultra precision lathes additionally equipped with Slow Tool and Fast Tool systems can be regarded as state-of-the-art machines achieving the objectives of high quality optical components. The mechanical design of such ultra precision machine tools as well as the mechanical integration of additional highly dynamic axes are very well understood today. In contrast to that, neither advanced control strategies for ultra precision machining nor the control integration of additional Fast Tool systems have been sufficiently developed yet. Considering a complex machine setup as a mechatronic system, it becomes obvious that enhancements to further increase the achievable form accuracy and surface quality and at the same time decrease cycle times and error sensitivity can only be accomplished by innovative, integrated control systems. At the Fraunhofer Institute for Production Technology IPT a novel, fully integrated control approach has been developed to overcome the drawbacks of state-of-the-art machine controls for ultra precision processes. Current control systems are often realized as decentralized solutions consisting of various computational hardware components for setpoint generation, machine control, HMI （human machine interface）, Slow Tool control and Fast Tool control. While implementing such a distributed control strategy, many disadvantages arise in terms of complex communication interfaces, discontinuous safety structures, synchronization of cycle times and the machining accuracy as a whole. The novel control approach has been developed as a fully integrated machine control including standard CNC （computer numerical control） and PLC （programmable logic controller） functionality, advanced setpoint generation methods, an extended HMI as well as an FPGA （field programmable gate array）-based controller for a voice coil driven Slow Tool and a piezo driven Fast Tool axis. As the new control system has been implemented as a fully integrated platform using digital communication via EtherCAT, a continuous safety strategy could be realized, the error sensitivity and EMC susceptibility could be significantly decreased and the overall process accuracy from setpoint generation over path interpolation to axes movements could be enhanced. The novel control at the same time offers additional possibilities of automation, process integration, online data acquisition and evaluation as well as error compensation methods.
