Micromilling of metal alloys with focused ion beam–fabricated tools

This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating metal alloy microcomponents. Micro-end mills having 25 μm diameters are made by sputtering cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks. A 20 keV focused gallium ion beam is used to define a number of cutting edges and tool end clearance. Cutting edge radii of curvature are less than or equal to 0.1 μm. Micro-end mill tools having 2, 4 and 5 cutting edges successfully machine millimeter long trenches in 6061-T4 aluminum, brass, 4340 steel and polymethyl methacrylate. Machined trench widths are approximately equal to the tool diameters, and surface roughnesses (R_a) at the bottom of micromachined features are 200 nm. Microtools are robust and operate for more than 6 h without fracture. Results from ultra-precision machining aluminum alloy at feed rates as high as 50 mm/minute and an axial depth of 1.0 μm are included.     

超光滑光学表面加工技术

现代科学技术的发展,在许多领域中提出了加工超光滑表面的要求。这种表面不仅要具备较高的面形精度和极低的表面粗糙度,同时要具有完整的表面晶格排布,消除加工损伤层。近年来国际出现了不少成功的超光滑表面加工技术,可以实现表面粗糙度小于1nm,面形精度优于30nm.本文介绍了超光滑表面的主要应用领域；从去除机理的角度讨论了BFP抛光、Teflon抛光、离子束加工、PACE加工、浮法抛光、延展性磨削等六种有代表性的超光滑表面加工技术；并对国内情况作了简单分析。     

超精密加工机床的关键部件技术

论述了亚微米级超精密加工机床的主轴、直线导轨、,进给与微量进给,隔振与恒温等关键元部件的设计原理、实施方案,及其在ＨＣＭ－１超精密加工机床中的应用。     

硬脆材料超光滑表面磨削技术的现状及发展趋势

概述了具有光滑表面的硬脆材料的应用前景，介绍了国内外在硬脆材料超光滑表面精密磨削技术上的发展现状，提出了获得硬脆材料超光滑磨削表面的主要技术措施，并从国情实际情况出发，提出了我国在超精密磨削技术方面今后应开展的研究工作。     

基于六轴数控铣齿机的点接触曲线圆柱齿轮加工仿真

点接触曲线圆柱齿轮是一种新型平行轴传动齿轮,用常规的机床和刀具难以完成其齿形的高效加工.利用六轴数控铣齿机和面铣式刀盘完成该齿轮的模拟加工.首先,根据该齿轮的成型原理,推导齿面的数学模型,求解齿面点云数据,基于点云数据在三维建模软件中构建齿轮实体模型;然后,在VERICUT中构建数控铣齿机和刀具,再编写齿轮加工的数控程...     

Contour offset algorithm (COA) in nano replication printing (nRP) for fabricating nano-precision features

A Contour Offset Algorithm (COA) has been developed to fabricate nano-precision figures or patterns in the range of several microns by a nano-Replication Printing (nRP) process. In the nRP process, a femtosecond laser illuminated on photosensitive monomer resin to induce polymerization of the liquid monomer according to a volume pixel (voxel) matrix which is transformed from a two-tone (black and white) bitmap file. After two-photon absorbed photo-polymerization (TPP), a droplet of ethanol is dropt on a glass plate to remove the unnecessary remaining liquid resin, leaving only polymerized patterns on the glass plate. In the nRP process, the replicated patterns do not precisely coincide with the initial designs due to an essential shortage of nRP process. Fabricated patterns by means of the nRP process become larger than the design in the amount of the voxel radius. In this work, an outer contour matrix of an initial design was constructed and reduced according to an offset-ratio calculated by the COA in order to obtain more precise patterns. Both the effectiveness and the accuracy of the proposed algorithm were demonstrated through chosen example.     

微加工多晶硅薄膜热导率T型测试结构的设计与模拟

提出了一种表面加工多晶硅薄膜热导率的T型测试结构。给出了热学模型和测试方法,并利用ANSYSTM软件进行模拟分析,验证了该测试方法是适用的。该测试方法能够实现多晶硅薄膜热导率的在线测试。     

光纤透镜研磨抛光的轮廓成形控制系统的研究

为了有效地减小光纤透镜的研磨抛光轮廓误差,设计一种两轴联动的交叉耦合轮廓控制器,并且针对光纤透镜研磨抛光机床的运动特点,给出了交叉耦合轮廓误差模型.然后利用Matlab软件对该交叉耦合轮廓控制的效果进行了仿真研究与分析.仿真结果表明,利用该控制器能使系统轮廓误差从0.075 μm减小到0.03 μm,但由于加入了交叉耦合器的补偿量,Z轴的跟随误差也从0.05 μm增大到0.07 μm.同时也表明两轴联动的交叉耦合控制系统远远优于单轴PID控制系统.     

"Derived spectra" software tools for detecting spatial and spectral features in spectrum images

A spectrum image is recorded as an x-y array of beam locations at each of which a spectrum of radiation is recorded as stimulated by the beam. The large database or "datacube" that results from a single image presents a significant challenge to the analyst to recover information efficiently, especially in the case where a true unknown is examined. This paper describes a class of "derived spectra" software tools that can aid the analyst in recognizing both common and rare features within the datacube. A derived spectrum tool creates a spectrum-like display (intensity vs. channel number) in which the intensity (e.g., x-ray counts) at a particular channel (e.g., x-ray photon energy) is calculated from all of or a subset of the pixel intensities measured for that channel. Derived spectra tools considered include the SUM, MAXIMUM PIXEL, RUNNING SUM, and RUNNING MAXIMUM. The SUM-derived spectrum is useful for recognizing common features of the datacube, while the MAXIMUM PIXEL-and RUNNING MAXIMUM-derived spectra can locate rare, unanticipated features, which may occur as infrequently as being present at a single pixel in the original datacube.     

Influence of the Redeposition effect for Focused Ion Beam 3D Micromachining in Silicon

The influence of the redeposition effect on the focused ion beam 3D micromachining process of silicon is discussed. Milling of some typical patterns in which redeposition is serious has been carried out. Experimental results are analysed in combination with a theoretical model. It can be seen from the analysis that the order of recycle-milling is very important for 3D microfabrication owing to redeposition during the process. In addition, the parameters of beam current, ion beam spot size, etc. are also key factors in the process. A groove and dome shape will be formed at the root of the sidewall and the bottom of the pattern, respectively, because of the ion sputtering yield bariation and sidewall redeposition. Finally, avoidance methods are suggested as a result of the analysis.     

A three-dimensional model for the dynamics of micro-endmills including bending, torsional and axial vibrations

Attainable geometric accuracy and surface finish in a micromilling operation depends on predicting and controlling the vibrations of micro-endmills. The specific multi-scale geometry of micro-endmills results in complexities in dynamic behavior, including three-dimensional vibrations, which cannot be accurately captured using one-dimensional (1D) beam models. This paper presents an analytically based three-dimensional (3D) model for micro-endmill dynamics, including actual cross-section and fluted (pretwisted) geometry. The 3D model includes not only bending, but also coupled axial/torsional vibrations. The numerical efficiency is enhanced by modeling the circular cross-sectioned shank and taper sections using 1D beam equations without compromising in model accuracy, while modeling the complex cross-sectioned and pretwisted fluted section using 3D linear elasticity equations. The boundary-value problem for both 1D and 3D models are derived using a variational approach, and the numerical solution for each section is obtained using the spectral-Tchebychev (ST) technique. Subsequently, component mode synthesis is used for joining the individual sections to obtain the dynamic model for the entire tool. The 3D model is validated through modal experimentation, by comparing natural frequencies and mode-shapes, for two-fluted and four-fluted micro-endmills with different geometries. The natural frequencies from the model was seen to be within 2% to those from the experiments for up to 90 kHz frequency. Comparison to numerically intensive, solid-element finite-elements models indicated that the 3D and FE models agree with less than 1% difference in natural frequencies. The 3D-ST model is then used to analyze the effect of geometric parameters on the dynamics of micro-endmills.     

超精密加工及其进给驱动技术

论述了超精密加工的重要意义、主要方法、一些关键技术及在机械制造技术中的作用和地位;介绍了一种直线电机直接驱动的新型超精密进给机构的工作原理和基本结构,较好地解决了超精密加工的精确移动和定位问题。     

均衡压力场平面抛光技术的研究

这里基于弹性力学的接触理论，研究了导向环、工件与抛光垫接触的压力场分布形态，提出了通过改变工件相对夹具的负载比，进行均衡压力场抛光技术的研究，较好地解决了大尺寸硅片的平面加工问题。使用该项技术可使半导体晶片抛光的平面度达到0．25—0．330μm/φ76mm。     

An automated Guilloche machining technique for the fabrication of polygonal Fresnel lens array

Fresnel lenses are gaining wider applications in optoelectronics and photonic devices. They have been evolved into arrays of individual elements with better performance and better capabilities. These arrays may also be realized with individual elements having polygonal shapes such as rectangular, hexagonal, etc to achieve a high fill factor. Due to the fact that the polygonal Fresnel lens arrays are not rotationally symmetrical, they are manufactured by using expensive lithography techniques or time consuming method of having multiple molds assembled together. This paper presents an automated 4-axis ultraprecision machining technique for manufacturing an array of hexagonal Fresnel lenses. In the proposed method, a diamond tool moves as a fixed point on a circle rolling inside a fixed circle which is analogous to a Guilloche machine. The proposed automated machining technique has been experimentally verified through successful manufacturing hexagonal Fresnel lens array in a single process, without having separated sections assembled as a single master mold. From the results, an excellent surface finish and good profile accuracy are also achieved. The developed automated Guilloche machining technique also paves the way for the promising challenges to remove manufacturing barriers of machining freeform surfaces with complex curvatures.     

Effects of the heat source profiles on the thermal distribution for ultraprecision grinding

In order to investigate the thermal effects on the workpiece during ultraprecision grinding processes, an analytical thermal model is firstly developed. Based on the established model, both the steady-state and the transient temperature distributions are obtained and the effects of the grinding parameters on the temperature distribution are analyzed. Various heat source profiles are utilized to simulate diverse ultraprecision grinding conditions, and the effects of the parameters of the heat source on the temperature distribution are investigated. The developed thermal model and analysis results provide further insights of the temperature distributions for ultraprecision grinding processes.     

High-efficiency approach for fabricating MTE rotor by micro-EDM and micro-extrusion

Micro-gas turbine engine（MTE） rotor is an important indicator of its property, therefore, the manufacturing technology of the microminiature rotor has become a hot area of research at home and abroad. At present, the main manufacturing technologies of the MTE rotor are directed forming fabrication technologies. However, these technologies have a series of problems, such as complex processing technology high manufacturing cost, and low processing efficiency, and so on. This paper takes advantage of micro electric discharge machining（micro-EDM） in the field of microminiature molds manufacturing, organizes many processing technologies of micro-EDM reasonably to improve processing accuracy, presents an integrated micro-EDM technology and its process flow to fabricate MTE rotor die, and conducts a series of experiments to verify efficiency of this integrated micro-EDM. The experiments results show that the MTE rotor die has sharp outline and ensure the good consistency of MTE rotor blades. Meanwhile, the MTE rotor die is applied to micro extrusion equipment, and technologies of micro-EDM and micro forming machining are combined based on the idea of the molds manufacturing, so the MTE rotor with higher aspect ratio and better consistency of blades can be manufactured efficiently. This research presents an integrated micro-EDM technology and its process flow, which promotes the practical process of MTE effectively.     

微结构气敏传感器制造工艺的研究

本文主要介绍了微结构气敏传感器制造工艺中的关键技术,例如双面光刻、反应等离子刻蚀、硅的各向异性腐蚀、采用溶胶—凝胶镀膜技术制备ＷＯ３敏感薄膜。文中还给出ＷＯ３薄膜的ＸＲＤ和ＳＥＭ表面分析图。对结构和表面形貌进行了分析,并给出传感器的气敏特性曲线。最后对存在的问题进行了简单的讨论。     

硅各向异性腐蚀模拟的3-D连续CA模型研究

针对硅的各向异性腐蚀，直接采用硅的晶格结构作为CA（元胞自动机）的晶格结构，建立了硅各向异性腐蚀的3D连续CA模型。模型通过引入更多腐蚀过程中出现的晶面，使得腐蚀过程中表层元胞边界条件的确定只与表层元胞有关，提高了模拟的精度。通过对模似结果的理论分析及将模拟的三维输出结果与已有实验结果进行对比，验证了模型的模拟效果。     

Nano-abrasion machining of brittle materials and its application to corrective figuring

A method of ultraprecision abrasion machining named “Nano-abrasion machining” is proposed for optical finishing of brittle materials. The fundamental characteristics and its applicability for corrective figuring to improve form accuracy of optics of brittle materials are investigated. It is experimentally ascertained that the material removal rate and surface roughness are suitable for optical finishing. However, the cross-sectional profile of the machined spot that is dependent on the collision angle is a combination of V- and W-shape, which is unsuitable for the corrective figuring. Therefore, circular motion machining is introduced and a preferable profile with an axis-symmetric V-shape is realized. The machining method is applied to corrective figuring of optical glass of BK7. The NC program is generated with a computer program developed by modifying the scanning motion and the form accuracy is predicted. According to the simulation results, corrective figuring is performed. The flatness is improved from PV = 151 to 29 nm. From the experimental results, it is clarified that the nano-abrasion machining is applicable to corrective figuring of brittle materials.     

Control of an equipment for fabricating periodic nanostructure

This study presents the control for an equipment that is designed for fabricating periodic nanostructures. This equipment can generate the patterns required for nanostructure production using direct writing laser lithography. The equipment incorporates a direct writing laser lithography instrument, a linear motor-driven long-stroke stage (X, Y), a piezoelectric-driven two degrees of freedom (2-DOF) nano-stage (Y, θ_z), a 3-DOF laser interferometer measurement system, and a system control unit. The working stage of this equipment is combined by a long-stroke stage and a nano-stage; therefore, it can provide long-stroke and high-precision positioning. The feedback signal for this stage is obtained using a 3-DOF laser interferometer measurement system. Integral sliding-mode controllers are used to control the linear motor-driven stage and PID controllers are used to control the piezo-stage for precision positioning. This paper presents the design of the controllers and the control results. Experimental results show that satisfactory writing results can be obtained at a 100 mm/s scan speed.