Progress of Precision Engineering and Nano Technology

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Authors: X.W. Sun, Fei Hu Zhang, Shen Dong, L.J. Zhang
Abstract: An ultra-precision machine is developed by Precision Engineering Research Institute of Harbin Institute of Technology to machine components made of KDP crystal with single point diamond fly cutting technique . A stable ultra-low speed feed of worktable is necessary in the machining process inasmuch as the KDP crystal components to be machined must be high form accuracy, low surface roughness and low surface waveness . This paper analyses the effect on speed stability and positioning accuracy under the control of semi-closed loop and full-closed loop based on the experimental data, and also present a compensating control algorithm of error disturbance feed-forward which enhances the stability of ultra-low speed motion of the semi-closed loop feed control servo system of the machine. The simulation results indicate that the values of the steadystate tracking error decreased to 1/10 after using compensating control algorithm. The P-V value of the aluminum specimen machined by the ultra-precision machine tool was 0.27 wavelengths.
Authors: Manabu Iwai, A. Sharma, Wei Li Pan, Sadao Sano, Tetsutaro Uematsu, Kiyoshi Suzuki
Abstract: It has been reported in our previous report that electrically conductive CVD diamond (hereafter, EC-CVD diamond) having specific resistance of the order of 1x10-3 Ω⋅m shows almost zero electrode wear even at the short pulse duration of 3μs on a die-sinking EDM machine. In this research EDM properties are investigated in the context of the pulse on time in oil and water. It is found that the electrode polarity has an effect on the electrode wear of the EC-CVD diamond electrode in oil. In the test in oil, EC-CVD diamond shows zero wear at positive [+] electrode polarity but a higher wear at negative [-] electrode polarity than that of the copper electrode. Furthermore, the EC-CVD diamond electrode showed very less wear than copper even in water. These results in oil and water may be due to the high thermal diffusivity, an increased rate of carbon adhesion and the high thermal stability of the EC-CVD diamond electrode. Workpiece surface roughness using the EC-CVD diamond electrode is about 20~50% lower than using the copper electrode under the same EDM conditions. From the single pulse discharge experiment with EC-CVD diamond and copper electrodes, the improvement in roughness is explained by the dispersion of the discharge in the case of EC-CVD diamond due to its rather high specific resistance.
Authors: Yan Ling Tian, Da Wei Zhang, Bing Yan
Abstract: In order to improve the machining accuracy of the precision surface grinding machine, a 3-DOF micropositioning table is used as an auxiliary table to form the dual infeed system with nanometer level positioning accuracy. This paper mainly deals with the static characteristics of the micropositioning table. The direct and inverse kinematic models are obtained under different orientation descriptions, and the inherent relationship between different orientation descriptions is investigated. By use of Eular angle description, the reachable orientation space of the micro-positioning table is obtained. The theoretical static stiffness on the top surface of the table is also given, and the experimental tests are carried out to verify the established models.
Authors: J.H. Wang, D.J. Lu, Zhuang De Jiang, X.N. Chen
Abstract: In recent years, there is an effort to develop a portable, autonomous micro power generation system to obtain an order of magnitude improvement in energy density over general alkaline or lithium ion batteries. As hydrocarbon fuels have much higher energy to weight ratios than general batteries, researches to realize micro-engines fueled by such hydrocarbon fuels are carried out in some universities or institutes. The first key problem of the researches is how to get a micro-engine structure suitable for MEMS (Micro-Electro Mechanical Systems) fabrication. This micro-engine structure needs characteristics such as planar geometry, self-valving operation and a minimal number of moving parts and so on. In this paper, a micro sliding rotary type combustion engine structure is presented and described. The intrinsic characteristics of the engine housing curve named of “kindred cardioids curve” are described in details. The structural scheme and cycle process of the micro-engine are discussed. Some performance parameters of the micro engine are theoretically calculated with H2-Air mixture and specified geometry parameters. The primitive calculated results indicate that the sliding rotary combustion engine is workable and effective.
Authors: Su Yu Wang, Xing Ai, Jun Zhao
Abstract: Predictive models are presented for the surface roughness in high-speed end milling of 0.45%C steel and P20 die-mould steel based on statistical test and multiple-regression analysis. The data for establishing model is derived from experiments conducted on a high-speed machining centre by factorial design of experiments. The significances of the regression equation and regression coefficients are tested in this paper. The effects of milling parameters on surface roughness are investigated by analyzing the experimental curves.
Authors: Y.H. Yang, Shi Jin Chen, K. Cheng
Abstract: A novel fast tool servo driven by piezoelectric actuator for precision diamond turning is designed in this paper. To overcome the inherent hysteresis and drift nonlinearity effect of the piezoelectric actuator, a closed-loop control system is established using strain gauge integrated in the actuator for position feedback, which has compact structure and can avoid interference in the machining. Furthermore, a fuzzy PI control algorithm is presented. It has not only the advantages of agility and adaptability of fuzzy control, but the characteristics of high accuracy of PI arithmetic. At last, experiments are carried out and the results show that the fuzzy PI control provides significantly better tracking accuracy and robustness against hysteresis and drift effects.
Authors: Y.J. Chen, Kuang Chao Fan, Y.S. Liu, F. Cheng
Abstract: An innovative high precision optical focus probe has been developed to measure the grating pitches. This probe uses characteristics of FES (focus error signal) of the modified DVD pickup head. Experimental tests showed the linear range of FES of this probe to the gratings was 5μm, the resolution was less than 1nm, the time stability was 5nm in 10 minutes, and positioning repeatability was better than 12nm. This system was applied to measure the grating pitch of 1200 lines per 1mm. The quality of the grating was assessed by the average of sampled pitches and its standard deviation. The inspected results can be an index to improve the process control of the grating fabrication.
Authors: Ying Chun Liang, J.H. Dou, Qing Shun Bai
Abstract: Carbon nanotubes (CNTs) represent ideal Atomic Force Microscope (AFM) tip materials due to their remarkable mechanical properties. Dynamic interactions of a Single-wall Carbon nanotube (SWCNT) indenting towards a monocrystalline hydrogen-free Silicon surface (001) are investigated using molecular dynamic simulation. The critical strain and strain force along the axis of the tube from elastic to plastic regimes are calculated. The simulation shows the deform process in elastic regimes is similar to the process of two ends inward compressed. The atoms of nanotube tip adsorption to the Silicon surface has been observed in the plastic regimes. The mechanical microprocess of AFM’s single-wall Carbon nanotube tip and Silicon surface interactions from elastic to plastic regimes can be well comprehended from the view of nanoscale energetic evolution.
Authors: Zhen Fan, B. Kan, J.N. Ding, Ping Yang
Abstract: Thin DLC film is in need for higher magnetic storage density. Surface modification and materials removal of DLC films were carried out in order to estimate the reliability of the ultra thin DLC films. Atomic force microscope (AFM) was used to investigate the wear resistance, surface modification and mechanical reliability of the films. Wear test by contact AFM indicated that wear depth under the same load was varied at different thick films. The local modification is studied using conductive atomic force microscope (C-AFM). Especially, topography change is observed when DC bias voltage applied. Experimental results show that the DLC surface is not modified after direct current applied on the tip. While positive voltage is applied on the DLC film surface, the nanoscale pit on the surface is formed clearly. According to the interaction force between CoCr coating MESP tip and the DLC film surface, as well as the Sondheimer oscillation theory, the “scale wing effect” of the pit is explained. Electromechanical coupling on the DLC film indicates that the depth of pit increases with the augment of force applied on surface when normal force is less than a certain threshold pressure.
Authors: Li Hua Lu, Yong Feng Guo, H. Tachikawa, Ying Chun Liang, Akira Shimokohbe
Abstract: This paper deals with nanometer positioning in the presence of friction. The object studied is a ball-screw-driven and linear-ball-guide-supported table system. For this system, the friction dominates the resulting performance for micro-motion and the system exhibits microdynamic characteristic which is rather different from macrodynamics. Inherently a controller with high loop-gain is needed to suppress the effect of friction. A PID controller is designed for the table system for step height smaller than 10μm. Experiment and simulation results indicate that the PID controller can provide a sufficiently high-loop gain and effect of friction is suppressed. In point-to-point(PTP) positioning for step heights from 10μm down to 10nm, the positioning error is within ±2 nm and the response dynamics is satisfactory.

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