超精神加工机床的模块化设计

分析了模块化设计的优点和超精密加工机床设计的现状,提出了超精密加工机床模块化设计的设想,并利用了模导伦超精密组件设计中典型的超精密机床。     

超精密静压支承部件及其在超精密加工机床的应用

超精密加工技术与装备在近年得到极大发展。超精密静压部件是超精密加工装备关键共性部件。以平面气体静压支承为例,介绍了静压支承基本工作原理。对超精密液体/气体静压主轴、导轨和转台的结构特点、技术特性、应用场合作了较全面的介绍;以典型超精密加工机床为例,介绍静精密静压主轴、导轨和转台在超精密加工机床中的应用。     

超精密加工机床的模块化设计

分析了模块化设计的优点和超精密加工机床设计的现状 ,提出了超精密加工机床模块化设计的设想 ,并利用了模块化超精密组件设计了几种典型的超精密机床。     

三坐标精密运动平台的设计

在超精密切削、磨削、特种加工中,大行程驱动与高精度进给是难以解决的矛盾,也是多坐标超精密加工的难点.本文以三维结构的超精密加工为对象,进行了适合超精密三维结构特种加工运动平台的设计,实现了较大行程的三维精密运动.该精密运动平台也是研制超精密加工机床的基础.     

基于PMAC的大型超精密车铣机床数控系统开发

以自行研制的基于工业PC机和PMAC卡的大型超精密车铣机床的开放式数控系统为对象，详细介绍了其硬件构成及控制、通讯原理，以及软件的结构和功能，简述了系统软件的编程。并分析了系统超精密定位和反馈检测性能，其能很好满足所装备的大型车铣机床的超精密定位和位置跟踪要求，实现机床的超精密、大行程的车铣加工。     

超精密机床数控伺服系统及其控制机理

介绍了一种超精密机床的数控伺服系统，分析了其硬件构成和各重要模块的特点，采用其装配的机床具备了加工大型光学零件的超精密定位和位置跟踪能力。并讨论了数控伺服系统所采用的先进双闭环控制理论，表明了其不仅具有高精度的位置控制功能，而且还有极高的稳定性和易调试性。     

超精密机床油液恒温控制系统的研究

用恒温油液喷淋机床是减小超精密机床热变形、提高热稳定性和改善零件加工精度的途径。为了得到恒温油液 ,作者用模糊控制器的单片机控制系统来控制机床油温 ,其温控精度可达± 0 2℃。     

基于压电陶瓷的微进给工作台及其控制系统的软硬件实现

论文提出并介绍了一种基于压电陶瓷的微进给工作台及其控制系统的软硬件实现方法。它是由压电陶瓷、柔性铰链机构和单片机控制系统所组成的系统。将该系统以一定的方式安装在已有磨削机构上，就可以实现对高精密零件的磨削加工，实验表明，它可以保证机床的最大定位误差小于0．04μm，最大归零误差小于0．04μm。该系统已经用在精密外圆磨床上完成对工件的超精密磨削加工。满足工件最大加工误差小于0．05μm。该系统不仅用在外圆磨床的精密进给上，还可以用在平面磨床和内圆磨床上实现对高精密零件的超精密加工。     

基于激光捕获原理的超精密加工技术研究

为了适应超精密加工对加工精度的要求,将激光捕获技术引入到超精密加工领域,提出了"基于激光捕获原理的超精密加工技术"的概念,介绍了其工作原理,建立了其理论模型,并通过组建基于激光捕获原理的超精密加工系统进行纳米加工,证明将激光捕获技术应用在超精密加工中是可行的.基于激光捕获原理的超精密加工技术为超精密加工提供了一种全新的工具,必将发挥越来越大的作用.     

精密与超精密磨削的发展现状

阐述了精密磨削与超精密磨削的机制,介绍了近年来精密与精密磨床的发展概况以及精密与超精密磨削技术的研究现状。在分析了精密磨削与超精密磨削的发展趋势基础上提出了研究应关注的几个热点问题,如超精密磨削的基本理论和工艺研究、研制高精度的驱动导向机构、ELID镜面磨削技术的攻关以及适用于超精密加工的新型材料。     

Ultra-precision grinding

Ultra-precision grinding is primarily used to generate high quality and functional parts usually made from hard and difficult to machine materials. The objective of ultra-precision grinding is to generate parts with high surface finish, high form accuracy and surface integrity for the electronic and optical industries as well as for astronomical applications. This keynote paper introduces general aspects of ultra-precision grinding techniques and point out the essential features of ultra-precision grinding. In particular, the keynote paper reviews the state-of-the-art regarding applied grinding tools, ultra-precision machine tools and grinding processes. Finally, selected examples of advanced ultra-precision grinding processes are presented.     

台式超精密车床关键部件结构设计

随着系统小型化已不断的成为一种趋势,微小精密零部件在很多领域都显示出越来越广阔的应用前景.目前,多数微小精密零部件都是由大型超精密机床加工的,由于大型超精密机床成本高,并难以控制其外界环境,使得其加工成本很高,因此,研制了台式超精密车床.本文介绍了该车床关键部件的设计,包括空气主轴、进给机构、快速伺服刀架等.该机床精度达亚微米级,不仅促进了微小型产品的制造与研究,而且加速了制造业的发展.     

Development of ultra-precision machining system with unique wire EDM tool fabrication system for micro/nano-machining

Aiming at quality machining of very hard materials with nanometer level surface quality and 0.1 μm dimensional accuracy, an ultra-precision machining system has been developed. The machine has feed axes accompanied by the counter motion mechanism driven at the center of gravity to eliminate the vibration caused by high acceleration/deceleration. A custom tool fabrication system consists of a 6-axis wire EDM machine and dedicated custom tool CAM system. High quality machining of sophisticated three-dimensional (3D) products made of tungsten carbide has successfully been demonstrated on the developed machine tool with custom-made PCD cutters fabricated by the tool fabrication system.     

Tool wear mechanisms and tool life enhancement in ultra-precision machining of titanium

Titanium and its alloys are generally considered as difficult-to-machine materials due to their poor thermal conductivity and high strength, which is maintained at elevated temperatures. This paper examines the tool wear mechanisms involved in ultra-precision machining of titanium. In this study single-crystal diamond tools were used to machine commercial pure titanium (CP-Ti) and Ti-6Al-4V alloy. Industrial expectations for surface quality and tool life based on optical grade applications are presented. Results obtained from the characterization of the tool, chip and workpiece led to the identification of graphitization as the mechanism that initiates tool wear. As the cutting edge rounds-off due to graphitization the rate of adhesion of the workpiece material onto the tool increased, which caused the quality of the surface finish to deteriorate. To reduce this wear mechanism a protective barrier made of Perfluoropolyether (PFPE) polymer, was explored. Tribometer studies with PFPE coated diamond tools and titanium pins showed a reduction in the coefficient of friction (COF). Subsequent machining tests using PFPE coated diamond tools showed promising results in extending the tool life and enhancing the surface quality to a point where Ti can now be considered as a viable option for applications involving optical grade surfaces.     

Tool path generation for ultra-precision machining of free-form surfaces

The generation of tool paths for ultra-precision machining is still a limiting factor in the manufacturing of parts with complex optical surfaces. In conventional machining as well as in complex five axes machining the application of CAD- and CAM-software for the generation of tool paths is state of the art. But these software solutions are not able to generate tool paths according to the high requirements of ultra-precision machining. This paper describes possible ways to generate tool paths for ultra-precision machining when the optical surface can be analytically described or when the surface data is derived from optical design software. Ultra-precision milling experiments with different tool paths have been carried out and the quality of the machined geometry has been evaluated concerning the achievable form accuracy.     

超光滑表面加工技术的发展及应用

超光滑表面加工技术是超精密加工体系的一个重要组成部分,超光滑表面在国防和民用等领域都有着广泛的应用.本文针对超光滑表面的需求,介绍了超光滑表面制造技术的发展过程,对各种超光滑表面加工原理与方法进行了简单描述与评价,最后提出了一种基于流体二维振动的超光滑表面加工技术,为超光滑表面的加工提供了新的方法.     

Development of monitoring system on the diamond tool wear

Recently, ultra-precision machining using a single crystal diamond tool has been developing very rapidly, especially in the fields of production processes for optical or magnetic parts such as magnetic discs, laser mirrors, polygon mirrors and copier drums. As a result, it has been successfully extended to machine various soft materials, generating mirror-like surfaces to sub-micron geometric accuracy with the ultra-precision CNC machine and the single crystal diamond tool. With the real cutting operation, the geometric accuracy and the surface finish attainable in machined surfaces are mainly determined by both of the sharpness of a cutting tool and stability of the machine vibration. In this study, for monitoring the progress of machining state for assuring the machining accuracy and the surface quality, a new monitoring method of machining states in face-cutting with diamond tool is proposed, using the frequency response of multi-sensors signal, which includes wear state of tool in terms of the energy within the specific frequency band. A magnetic disc is machined on the ultra-precision lathe.     

Performance evaluation of pure CBN tools for machining of steel

Ultra-precision machining is one of the most important machining technologies for the manufacture of precision dies and molds. Typically, single point diamond cutting tools are used to machine molds which are coated with electroless nickel (NiP) for such applications. The high cost of diamond cutters and electroless nickel plating, coupled with problems of pre-mature failure of the coating in service and long lead time are negative factors in this approach. Hence, there is a strong need for the direct ultra-precision machining of mold steel and to develop relevant technologies to address the problem of tool wear. In the machining of alloy steel, cubic boron nitride (CBN) has long been used as an ideal cutting tool material but recently binderless CBN or pure CBN (PCBN) with superior mechanical properties has been developed by Sumitomo Electric Industries in Japan. The objective of this paper is to explore the feasibility of using PCBN tools for direct ultra-precision machining of Stavax, a type of alloy steel from ASSAB. The performance characteristics in terms of surface roughness and tool wear of PCBN (Sumitomo IZ900) and conventional CBN (Sumitomo BN600) under different machining conditions were studied and their results were compared. Based on the experimental results, PCBN has been found to perform better in terms of wear resistance compared to conventional CBN tool. It is also able to achieve near mirror finish of less than 30 nm R_a, and hence it appears to be a promising tool for direct cutting of die and mold materials.     

Elliptical Vibration Cutting of Tungsten Alloy Molds for Optical Glass Parts

Elliptical vibration cutting is applied to ultra-precision machining of tungsten alloy molds for optical glass parts in the present research. The tungsten alloy is expected as a new mold material instead of conventional ones such as sintered tungsten carbide and CVD-silicon carbide. However, it cannot be finished precisely by ordinary cutting because of rapid tool wear, brittle fracture and adhesion to the tool. Therefore, the ultrasonic elliptical vibration cutting is applied to the ultra-precision machining of tungsten alloy. Practical ultra-precision molds are obtained by the elliptical vibration cutting, and they are applied to glass molding successfully.     

Ultra-precision machining of Fresnel microstructure on die steel using single crystal diamond tool

With the increasing demand for the replication of structured optical elements such as Fresnel lenses and prism arrays, more attention is being paid to the development of ultra-precision diamond machining technology for the fabrication of die steel molds. However, the machining process would be a catastrophic failure because of rapid and excessive tool wear if a diamond tool is used to machine die steel. In the present paper, a micromachining method for fabricating microstructures on die steel using single crystal diamond tool is presented. The presented technology is based on a thermochemical technique that uses plasma nitriding treatment to suppress the rapid and excessive tool wear in the diamond machining of steel. Experimental findings revealed that severe chemical tool wear, which is the main wear mechanism in the diamond machining of steel, was reduced significantly after plasma nitriding treatment, and a mirror-quality surface with an average surface roughness of 20 nm root-mean-square (RMS) was achieved over a cutting distance of approximately 5.4 km. Furthermore, a Fresnel microstructure with surface roughness RMS better than 40 nm was precisely fabricated on AISI 4140 die steel using single crystal diamond tool.