摘要
近年来,精密光学零件的应用越来越多,在民用、国防以及空间科学等领域都有着广泛的需求;而光学零件加工最重要的设备是超精密机床。超精密机床具有良好的加工性能是光学零件质量的重要保证。但是决定超精密机床性能的因素较多,导轨部件是其中之一。超精密机床导轨一般具有较高刚度和直线度,设计时通常采用了闭式液体静压形式。实际中,工作台受到载荷作用,滑块相对初始位置会发生偏移,该偏移对液体静压导轨的静态性能产生影响。此外导轨幅板在油膜压力的作用下发生变形,进而对导轨的刚度和直线度等性能产生影响,而关于该方面的研究却比较少。
本文根据微细结构加工超精密机床的总体技术指标设计了闭式液体静压导轨,从滑块的偏移和幅板变形两个方面出发,分析了其对液体静压导轨静态性静的影响,并通过模态的仿真与实验分析,对液体静压导轨的动态特性进行研究。根据液体静压支承工程设计方法确定了液体静压导轨的结构参数。推导了滑块偏移量与静态刚度、承载力和流量的关系公式,绘制了关系曲线,分析了滑块偏移对导轨静态性能的影响,确定导轨滑块的位移率。
利用有限元分析软件ANSYS对液体静压导轨进行了结构静态特性分析。通过弹性体模拟油膜,实现油膜压力随间隙的变化。得到了液体静压导轨的幅板变形量。经过对幅板变形量的分析,得到了导轨对置油膜的静态刚度以及幅板变形对导轨直线度的影响。
对液体静压导轨进行动态特性分析,分别采用仿真与实验两种方法,得到了液体静压导轨的固有频率和模态振型;并对仿真结果与实验结果进行了对比分析,验证有限元模型的正确性。通过对实验数据的分析,得到了静压导轨结合面的阻尼模态参数,为液体静压导轨动态性能分析提供依据。
In recent years, optical parts are used more and more widely in civilian use, national defense and space technology. Ultra-precision machine tools are the most important equipment for optical machining. The equality of optical parts is guaranteed by the characteristics of ultra-precision machine tools. However, there are many factors which affect on these characteristics, guideway is an important factor. In order to make the guideway have higher stiffness and guiding precision, the closed hydrostatic guideway is designed. In facts, the work table must carry load, so the slider will have an offset which will affect on the static characteristics of hydrostatic guideway. Otherwise, guideway rails deform under oil pocket pressure, which will affect on guideway stiffness and guiding precision, but a little research on rail deformation has been done.
The hydrostatic guideway is designed for ultra-precision machine tools according to the design standard, and the static characteristics of guideway are analyzed considering slider offset and rails deformation. Meanwhile, the dynamic characteristic of guideway is analyzed using simulation and experiment analysis.
The design targets are obtained with analyzing the machinability of ultra-precision machine tools, and then determine the structure of guideway. The design parameters are obtained with the method of existing hydrostatic bearing.. The relationship formations of slider offset and stiffness, carrying capacity and guiding precision are obtained respectively. And the relationship curves are protracted. The effect of slider offset on hydrostatic guideway is analyzed and the slider offset ratio is selected.
The static characteristics of hydrostatic guideway are analyzed using ANSYS in the third chapter. An elastomer of virtual material properties is used to simulate oil film, so that the relationship of oil film clearance and pressure can be represented in a certain range. The rails deformation is obtained after the establishment of the FE model of guideway. As follow, the effect of rails deformation on stiffness and guiding precision can be analyzed.
The simulation and experimental methods are used to analyse the dynamic characteristics. And the nature frequency and mode shape are obtained. After analyzing the difference of simulation and test, the correctness of FE model can be verified and damping model parameters can be calculated which can provide the basis for analysis of dynamic of guideway.
引文
1袁哲俊.精密和超精密加工技术的新进展.工具技术. 2006, 40(3):1~6
2李圣怡,戴一帆,彭小强.超精密机床及其新技术发展.国防科技大学学报. 2000, 22(2):95~100
3曹君蓬,杨辉.液体静压导轨及其驱动系统的研究.航空精密制造技术. 2002, 38(3):35~37
4丁振乾.我国机床液体静压技术的发展历史及现况.精密制造与自动化. 2003,3:19~21
5 B.B.ъушуев.李洪刚译.超精密机床.国外金属加工. 2002, 4:54~61
6欧阳渺安.超精密非球面模具直轴磨削的研究.光学精密工程. 2006,14(4):545~551
7罗松保,张建明.非球面曲面光学零件超精密加工装备与技术. 2002
8 Rank Pneumo Co.. Nanoform 600: Catalog. 1992
9 Suzuki, H. Niino, Y. Murakami, S. and Namba, Y.. Development of Ultra-precision Grinding Machinefor Grazing Incidence X-ray Mirrors. J. of JSPE, 1994,60(9):1309~1313,
10 Chun Hong Park, Yoon Jin Oh, Joo Ho Hwang and Deug Woo Lee. Development of an Ultra Precision Hydrostatic Guideway Driven by a Coreless Linear Motor. International Journal of Precision Engineering and Manufacturing. 2005, 6(2):55~60
11 Dzodzo, M., Braun, M. J. and Hendricks, R. C. Pressure and flow characteristics in a shallow hydrostatic pocket with rounded pocket/land joints. Tribology Int., 1996,29(1):69~76.
12 Xuedong Chen, Jin Lei. The Dynamic Modeling and Dynamics Response Analysis of Ultra-precision Drive Machine, Nano/Micro Engeered and Molecular Systems, 2008:828~833
13庞占东.大型超精密机床液压轴系幅板结构优化设计.哈尔滨工业大学. 2007
14孙学赟,罗松保.液体静压导轨的动态建模方法的研究2.航天学会2005年学术交流论文集, 2005:61~67
15 T.Nakamura, S.Yoshimoto. Static Tilt Characteristics of Aerostatic Rectangular Double-pad Thrust Bearings with Double Row Admissions. Tribology International. 1997,8(30):605~611
16黄华志.工具机液压轴承产品介绍与分析.工具机技术专辑. 2008, 300:58~72
17李炳健.液体静压导轨在机床中的应用.山西机械. 2003, 3:46~47
18曹君蓬,杨辉.液体静压导轨及其驱动系统的研究.航空精密制造技术. 2002, 38(3):35~37
19 Grag, H.C., Sharda, H.B., and Kumar V.. On the Design and Development of Hybrid Journal Bearings: a Review. Tnbotest. 2006,12:11~9
20 Rowe, W.B.. Hydrostatic and Hybrid Bearing Design. Butterworth&Co.Ltd.. 1983,15:35~40
21卢华阳,孙首群.液体静压导轨支承油膜的有限元分析.机床与液压. 2007,35(10):46~49
22朱希玲等.有限元数值模拟在静压轴承设计中的应用轴承.机械设计. 2005 (11):1~31
23吴晓元等.有限元法在球磨机静压轴承设计中的应用机械设计.机械设计. 2003 (6):25 ~261
24 Fazil Canbulut, Cem Sinanoglu, Sahin Yildirim. Analysis of Effects of Sizes of Orifice and Pocket on the Rigidity of Hydroctatic Bearing. 2004,18(3):432~442
25 Xiaodong Yu, Yanqin Zhang, Junpeng Shao. Numerical Simulation of Gap Flow of Sector Recess Multi-pad Hydrostatic Thrust Bearing. Asia Simulation Conference—7th Intl. Conf.on Sys. Simulation and Scientific Computing. 2008:675~679
26 M.F.Chen,W.L.Huang,Y.P.Chen. Design of the Aerostatic Liner Guideway with a Passive Disk-spring Compensator for PCB Drilling Machine. Tribology International. 2010,43:395~403
27孟心斋,孟昭焱.恒流供油液静压支承静态性能新表达式与应用.洛阳工学院学报. 2002,23(1):63~66
28于晓东.重型静压推力轴承力学性能及油膜态数值模拟研究. 2007
29 S Y Jeon , K H Kim. A fluid Film Model for Finite Element Analysis of Structures with Linear Hydrostatic Bearings. Mechanical Engineering Scince. 2004,218:309~316
30孟心斋,杨建玺,孟昭焱.液体静压支承动态性能新表达式探索与实验验证.中国工程科学. 2003,5(3):62~66
31陈学东.超精密气浮定位工作台技术.武汉:华中科技大学出版社. 2007
32庞志成.液体静压支承动态稳定性理论研究.哈尔滨工业大学学报. 1982,3:86~98
33张新宇,陈忠基,姚瑶,吴晓元.基于有限元法的气浮支承系统的数值模拟与实验研究.辽宁科技大学学报. 2008,31(3-4):285~287
34 T.OnatEkinci, J.R.R.Mayer, GuyM.Cloutier. Investigation of Accuracy ofAerostatic Guideways. International Journal of Machine Tools & Manufacture 49 (2009) 478–487
35 N.C.Das. A Study of Optimum Load Capacity of Slider Bearings Lubricated with Power Law Fluids. Tribology International. 1999, 32:435~441
36杨托.机床结构动力学建模技术的研究及在MGK7350平面磨床有限元分析中的应用.浙江工业大学. 2008
37刘悦,王立平,关立文.基于结合面的龙门五面加工中心虚拟建模及静态刚度研究.工具技术. 2007,41(5):14~17
38沈晓庆,翁泽宇,杨托,袁卫华,梅金虎.数控机床滚动导轨结合面参数的特性分析.研究·开发. 2009,534(47):30～32
39 Won-Jae Lee, Seok-ll Kim. Joint Stiffness Identification of an Ultra-Precision Machine for Machining Large-Surface Micro-Features, International Journal of Precision Engineering And Manufacturing. 2009,10(5):115~121
40 Chun Hong Park, Chang Kyu Song, Jooho Hwang and Byung-Sub Kim. Development of an Ultra Precision Machine Tool for Micromachining on Large Surfaces. International Journal of Precision Engineering and Manufacture. 2009,10:85~91
41陈燕生.液体静压支承理论.国防工业出版社. 1980
42 Ansys Inc. Structure Analysis Guide, Release 11.0 Documentation for ANSYS
43 Ansys Inc. Model Analysis Guide, Release 11.0 Documentation for ANSYS
44师汉民.机械振动系统—分析·测试·建模·对策.华中科技大学出版社. 2004:217～223
45贾宝贤,王振龙,赵万生.适用于微机械制造的常规加工方法.机械加工与自动化. 2003,(8):19~21
46管迪华.模态分析技术.清华大学出版社1994:52~69