Progress of Precision Engineering and Nano Technology

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Authors: Yong Feng Guo, Ji Cheng Bai, Guan Qun Deng, Ze Sheng Lu
Abstract: Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. This paper investigates the high speed wire electrical discharge machining (HS-WEDM) of Si3N4-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied and the optimized machine pulse width was got. The material removal mechanisms change with the increase in the power of single pulse.
281
Authors: Sandy To, Chi Fai Cheung, Su Juan Wang, Wing Bun Lee
Abstract: Optical communication is gaining popularity in telecommunications; most obviously evident is the increase in demand for a large variety of fiber optic components. V-groove structure quality is critical to the functionality of the fiber connector as it governs the position of the optic fibers. The main parameters, which determine the V-groove quality, include core pitch, surface roughness and the position of centerline. In this paper, a series of cutting conditions were applied to investigate the effect of different machining parameters on the V-groove quality. In the experiment, the V-groove structure is machined by a 40° single crystal diamond tool on aluminium alloy with different cutting conditions. Based on the findings, the relationship between the cutting conditions on the surface roughness was explored. The implications of these findings on the improvement of the surface finish of V-groove profile are discussed.
286
Authors: L.G. Chen, L.N. Sun, Y.X. Liu, H.X. Wang
Abstract: Molecular techniques are transforming our understanding of cellular function and disease. However, accurate molecular analysis methods will be limited if the input DNA, RNA, or protein is not derived from pure population of cells or is contaminated by the wrong cells. A novel Ultrasonic Vibration Microdissection (UVM) method was proposed to procure pure population of targeted cells from tissue sections for subsequent analysis. The principle of the Ultrasonic Vibration Cutting is analyzed, and a novel microknife is designed. A multilayer piezoelectric actuator is used to actuate a sharp needle vibrating with high frequency and low amplitude (Approx. 16–50 kHz, and 0-3μm) to cut the tissue. Contrast experiment was done to test the feasibility of UVM method. Experimental results show that the embedded tissue can be quickly and precisely cut with the ultrasonic vibration micro-dissection method.
291
Authors: Shi Chun Di, R.N. Huang, Guan Xin Chi, W.S. Zhao
Abstract: A new Micro-WEDM machine is developed in this paper. Therefore, experiment can be done on this machine. Especially, the surface characteristics of work-pieces are analyzed in detail. The Micro-WEDM can machine micro slot easily. In addition, all kinds of micro shaped holes, micro gears, complex micro parts and dies are machined to check its processability. A micro gear can be easily fabricated by micro-forming method with the micro gear dies fabricated by micro-WEDM, and get well performance, which indicates that micro parts machined by Micro-WEDM meet the requirements of micro instrument and device.
297
Authors: Zhong Ning Guo, F.Z. Zeng, G.H. Han, Zhi Gang Huang
Abstract: A new method for on-line fabrication of micro tool-electrodes is presented in this paper. The method is base on the machining mechanism of electrochemical micromachining. By exchanging the polarities of the tool-electrodes and workpiece repeatedly, micro tool-electrode appropriate for electrochemical micromachining can be obtained through mutual machining. Because the processes are carried out on-line, the position error and clamp error caused by twice-clamp of tool-electrodes can be avoided, and the machining precision can be improved greatly. This method will be very important to electrochemical generating micromachining. Experiments are carried out, and a tool-electrode with the pinpoint of 20μm can be machined stably.
302
Authors: J.F. He, H.Z. Jiang, D.C. Cong, Zheng Mao Ye, Jun Wei Han
Abstract: Based on extensive study on literatures of control of parallel manipulators and serial manipulators, control strategies such as computed torque control, PD+ control, PD with feedforward compensation, nonlinear adaptive control are classified into two categories: model-based control and performance-based control. Besides, as advanced control strategies, robust control and passivity-based control for the parallel manipulators are also introduced. Comparative study in view of computation burden and tracking performance are performed. It turned out that the physical structure properties of parallel manipulators’ dynamics are similar with that of serial ones, and this constitutes a common foundation for the two kinds of manipulators to develop together that control design of parallel manipulators can start with ever established control methods of serial manipulators.
307
Authors: D.B. Kang, S.M. Son, J.H. Ahn
Abstract: A workpiece with a large surface area is likely to be uneven due to form error and waviness. These geometric disturbances can cause inaccurate micro shapes to be formed when micro features are micro-grooved into the surface and cause the resulting workpiece to fail to function as desired. Thus, the real-time monitoring and compensation is required to guarantee the form accuracy of micro features while machining the workpiece with a large surface area. In this study, a method is suggested for real-time measurement and compensation of geometric errors for the micro grooving of a large flat surface using a laser displacement sensor placed ahead of the cutting tool. Experimental results show that the compensated surface profiles fit the measured ones within an allowable tolerance even at cutting speeds as high as 200 mm/s.
314
Authors: J.H. Lee, Wei Wang, Sung Hwan Kweon, Young Shin Kim, Young Moon Lee, Seung Han Yang
Abstract: The procedure of structural design on miniaturized machine tool (mMT) is proposed and structural optimization by applying robustness evaluation method is presented in this paper. The design procedure of a kind of mMT which is a 3-axis miniaturized milling machine tool (mMMT) is discussed and three different structures of mMMT are proposed based on previous design procedure. The most suitable structure is selected using robustness evaluation method, which is Taguchi method, due to volumetric error function. The design parameters of selected structure are optimized.
321
Authors: Xiao Hai Li, Zhen Long Wang, W.S. Zhao, Fu Qiang Hu
Abstract: This research work aims to explore the feasibility of applying electrochemical machining (ECM) to micromachining. An experimental setup for micro-ECM has been developed. Lower machining voltage, lower concentration of passivity electrolyte, high-frequency short-pulse power supply and micro tool electrode rotating at high speed have been synthetically adopted to localize the dissolution area in micro-ECM, so the machining gap can be kept at about 10 μm and the better resolution of machined shape is achieved. A micro-hole with 45μm diameter is drilled on the stainless steel foil with 100μm thickness. A new approach of fabricating microstructure by micro-ECM milling with a simple micro electrode is proposed, and the micro beam with width of about 50μm which has high precision is fabricated by micro-EC milling on the stainless steel foil (1Cr18Ni9Ti) with 300μm thickness. A mathematics model has been established, which can be used to simulate the process of shaping workpieces in the process of micro-ECM.
327
Authors: Xiang Yang Liu, D.W. Yu, X.J. Cai, H. Huang
Abstract: A feeding table system is set up to meet the need for high motional precision and super-slow speed in micro-electron discharge machining (micro-EDM). It is composed of a resonant piezoelectric ceramics motor, a linear bearing and a linear encoder . It features high accuracy due to the application of linear driving, closed-1oop feedback and elimination of abbe’s errors. The characteristics of fine motion , slow speed and load capability are investigated. The results of the experiments show that the stable fine motion of this system can be as little as 100 nanometer and its speed can be as slow as 0.5 micron per second which is proper for feeding table of micro-EDM.
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