超精密金刚石车床热态特性分析
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摘要
超精密加工设备是发展超精密加工技术的必要手段,国内外学者对超精密机床的静态特性、动态特性和热态特性进行了大量的研究,研究结果表明,在精密加工中,热变形引起的制造误差,占总制造误差的40%-70%,故对超精密机床进行热态特性分析尤为必要。本文研究了超精密金刚石车床的热态特性,为超精密金刚石车床的结构优化设计提供参考。
采用空气静压轴承的主轴作为超精密金刚石车床最为关键的部件,其性能的好坏直接影响到超精密金刚石车床的加工精度。本文建立了空气静压轴承处气膜的导热模型,求解了不同转速下的气膜温升。通过推导得到空气静压轴承气隙对流散热系数,并通过经验公式计算得到主轴其他部位的对流散热系数,最后在大型有限元分析软件ANSYS中建立主轴和电机转子的有限元模型,对主轴在不同转速下的稳态温度场和热变形进行分析,绘制了主轴温度-转速曲线、热变形-转速曲线,最终验证主轴转速达到最高设计转速时不会出现主轴卡死的现象。
作为超精密金刚石车床另一关键部件,液体静压导轨的静、动态特性对超精密金刚石车床的定位精度及加工精度有较大的影响,而采用直线电机驱动的液体静压导轨的热特性对机床加工精度的影响不容忽视。本章通过建立液体静压导轨的动导轨有限元模型,利用有限元分析软件ANSYS分析动导轨在不同工作环境下做不同运动时的热变形,提出减少液体静压导轨热变形的方法,避免导轨热变形对机床加工精度造成较大影响。
本文还对所有内热源共同作用下超精密金刚石车床的热态特性进行分析,得到了整机的稳态温度场分布云图,同时得出主轴电机热量传导的路径;并对整机结构的热态热性进行评价。设计了主轴电机的水冷系统,并通过ANSYS仿真得到水冷系统的冷却效果。通过ANSYS仿真得到环境温度变化对加工精度的影响。最后讨论了主轴前端热伸长对零件表面加工质量的影响,并提出了针对本机床的热误差补偿的方案。
Ultra-precision manufacture equipment is prerequisite for the development of Ultra-precision manufacture technology. Domestic and foreign scholars have done a lot of research on the static characteristics, dynamic characteristics and thermal characteristics on the ultra-precision machine tools. The results of the study show that 40%-70% of the machine tools’error is caused by is the thermal deformation of machine tools, so it has a great sense to analyse the thermal characteristics of the machine tools. In this paper, thermal characteristics of an ultra-precision diamond lathe are studied.
The spindle adopting aerostatic bearing is the most important component of the ultra-precision diamond lathe.Thermal conductivity model of the gas film in the aerostatic bearing is established, and the temperature rise under different revolution is calculated in this paper. The heat convection coefficient in the air-gap of aerostatic bearing and on the other outside surfaces of the spindle are calculated. Finally the steady-state temperature field and thermal deformation under different revolution of spindle are analyzed by ANSYS, and temperature curve and thermal deformation curve under different spindle revolution are plot. The result shows that the stuck of spindle won’t happen when the revolution reaches the highest design revolution.
To reduce the influence of thermal deformation of hydrostatic guide to the lathe, the finite model of moving guide of hydrostatic guide is established in this paper, then the thermal characteristics of moving guide under different working conditions are analyzed by using ANSYS. Simulation results show that the thermal deformation of moving guide is big when it is doing high-speed variational acceleration motion. Finally the methods of reducing thermal deformation of hydrostatic guide are proposed.
This paper also analyzes the thermal characteristics of the ultra-precision diamond lathe under all internal heat source. The lathe's steady-state temperature field is plot and the heat conduction paths from spindle motor are pointed out. Then the thermal characteristics of the whole structure of lathe is evaluated. A water cooling system of spindle system is designed. And the effect of water cooling system is simulated by ANSYS. How the environment temperature change affects the machining accuracy is also analyzed. Finally the influence of the spindle front-end extension to the microstructure surface processing is discussed, and an thermal error compensation scheme is proposed.
采用空气静压轴承的主轴作为超精密金刚石车床最为关键的部件,其性能的好坏直接影响到超精密金刚石车床的加工精度。本文建立了空气静压轴承处气膜的导热模型,求解了不同转速下的气膜温升。通过推导得到空气静压轴承气隙对流散热系数,并通过经验公式计算得到主轴其他部位的对流散热系数,最后在大型有限元分析软件ANSYS中建立主轴和电机转子的有限元模型,对主轴在不同转速下的稳态温度场和热变形进行分析,绘制了主轴温度-转速曲线、热变形-转速曲线,最终验证主轴转速达到最高设计转速时不会出现主轴卡死的现象。
作为超精密金刚石车床另一关键部件,液体静压导轨的静、动态特性对超精密金刚石车床的定位精度及加工精度有较大的影响,而采用直线电机驱动的液体静压导轨的热特性对机床加工精度的影响不容忽视。本章通过建立液体静压导轨的动导轨有限元模型,利用有限元分析软件ANSYS分析动导轨在不同工作环境下做不同运动时的热变形,提出减少液体静压导轨热变形的方法,避免导轨热变形对机床加工精度造成较大影响。
本文还对所有内热源共同作用下超精密金刚石车床的热态特性进行分析,得到了整机的稳态温度场分布云图,同时得出主轴电机热量传导的路径;并对整机结构的热态热性进行评价。设计了主轴电机的水冷系统,并通过ANSYS仿真得到水冷系统的冷却效果。通过ANSYS仿真得到环境温度变化对加工精度的影响。最后讨论了主轴前端热伸长对零件表面加工质量的影响,并提出了针对本机床的热误差补偿的方案。
Ultra-precision manufacture equipment is prerequisite for the development of Ultra-precision manufacture technology. Domestic and foreign scholars have done a lot of research on the static characteristics, dynamic characteristics and thermal characteristics on the ultra-precision machine tools. The results of the study show that 40%-70% of the machine tools’error is caused by is the thermal deformation of machine tools, so it has a great sense to analyse the thermal characteristics of the machine tools. In this paper, thermal characteristics of an ultra-precision diamond lathe are studied.
The spindle adopting aerostatic bearing is the most important component of the ultra-precision diamond lathe.Thermal conductivity model of the gas film in the aerostatic bearing is established, and the temperature rise under different revolution is calculated in this paper. The heat convection coefficient in the air-gap of aerostatic bearing and on the other outside surfaces of the spindle are calculated. Finally the steady-state temperature field and thermal deformation under different revolution of spindle are analyzed by ANSYS, and temperature curve and thermal deformation curve under different spindle revolution are plot. The result shows that the stuck of spindle won’t happen when the revolution reaches the highest design revolution.
To reduce the influence of thermal deformation of hydrostatic guide to the lathe, the finite model of moving guide of hydrostatic guide is established in this paper, then the thermal characteristics of moving guide under different working conditions are analyzed by using ANSYS. Simulation results show that the thermal deformation of moving guide is big when it is doing high-speed variational acceleration motion. Finally the methods of reducing thermal deformation of hydrostatic guide are proposed.
This paper also analyzes the thermal characteristics of the ultra-precision diamond lathe under all internal heat source. The lathe's steady-state temperature field is plot and the heat conduction paths from spindle motor are pointed out. Then the thermal characteristics of the whole structure of lathe is evaluated. A water cooling system of spindle system is designed. And the effect of water cooling system is simulated by ANSYS. How the environment temperature change affects the machining accuracy is also analyzed. Finally the influence of the spindle front-end extension to the microstructure surface processing is discussed, and an thermal error compensation scheme is proposed.
引文
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[26]邓三鹏.基于热误差补偿的加工中心在线检测软件的研究[J].机床和液压,2004,2:151-153.
[27] http://baike.baidu.com/view/2655944.htm
[28]王泽鹏. ANSYS12.0热力学有限元分析从入门到精通[M].北京:机械工业出版社,2010.
[29] E.Creighton, A.Honegger, A.Tulsian, D.Mukhopadhyay. Analysis of Thermal Errors in a High-speed Micro-milling Spindle. International Journal of Machine Tools and Manufacture, 2010, 50 (4):386-393.
[30]曹骏,胡佩俊,应济.基于接触热阻的主轴热特性有限元分析[J].机电工程,2008,25(2):20-22.
[31] Zhao Haitao, Yang Jianguo, Shen Jinhua. Simulation of Thermal Behavior of CNC Machine Tool Spindle[J]. International Journal of Machine Tools and Manufacture, 2007, 47(6):1003-1010.
[32]马晓波. SYSK-209型管子车丝机主轴箱热特性研究[D].长春:吉林大学机械制造及其自动化专业硕士学位论文,2006.
[33]石彦华,周华. CXK630五轴联动车铣复合加工机床高速主轴热态特性分析[J].机床与液压,2009,37(6):35-36,41.
[34]胡秋,何东林.数控机床电主轴单元热-结构特性动态分析[J].设计与研究,2006,12:5-7.
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[2] Bryan, J.B.. International Status of Thermal Error Research[J]. Annals of the CIRP, 1968, 16(2):203-215.
[3] Weck,M., McKeown, P.A.. Reduction and Compensation of Thermal Errors in Machine Tools[J]. Annals of the CIRP, 1995, 42 (2):589-598.
[4]陈兆年,陈子辰.机床热态特性学基础[M].北京:机械工业出版社,1989.
[5] G.Spur, H.Fisher. Thermal Behaviour of Machine Tools[J]. 10th International MTDR Conference, 1969.
[6]恒也一昭.工作机械の热变形と加工精度[J].机械と工具,1977,10.
[7]闫占辉,于骏一.机床热变形的研究现状[J].吉林长春自然科学学报,2001,31(3):95-97.
[8] Toshimichi, MORIWAKI. Thermal Deformation of Machining Center Due to Temperature Change in the Environment. Transactions of the Japan Society of Mechanical engineers, 1991, 57(539):2447- 2452.
[9] Jung Do Suh, Dai Gil Lee. Thermal Characteristics of Composite Sandwich Structures for Machine Tool Moving Body Applications[J]. Composite Structrues, 2004, 66 (/1-4):429-438.
[10]何学农.红外热像仪在电机检测方面的应用[J].今日电子,2008,6:32-32,35.
[11] Hansen H J. Techniques for precision Air-temperature Control[C]. Proceedings of 27 Annual International Technical Symposium on High Speed Photography, Videography and photonics, San Diego, CA, USA, 1983:80-91.
[12]张日升,李尚政,刘宏,等.精密加工局域温度控制研究[J].机械,2000,29(增刊):26-28.
[13]王金生,郑雪梅,汪超.减少机床热变形方法的研究[J].机床与液压,2006,2:88-90.
[14] M. Donmez, M. Hahn, J. Soons. A Novel Cooling System to Reduce Thermally-Induced Errors of Machine Tools[J]. Annals of CIRP, 2007, 6(1):521–524.
[15] Robert C. Wetherhold, Steven Seelman, Jianzhong Wang. The use of functionally graded materials to eliminate or control thermal deformation[J]. Composites Science and Technology, 1996, 56(9): 1099-1104.
[16]胡金祥,蒋书运,黄国庆.高速内圆磨床工件主轴系统热特性分析.精密制造与自动化,2007,1:10-13.
[17] RAMESH R,MANNAN M A,POO A N.Error compensation in machine tools-a review: Part II: Thermal errors[J].International Journal of Machine Tools and Manufacture, 2000, 40(9): 1257-1284.
[18] SHEN Jinhua, YANG Jianguo. Application of partial least squares neural network in thermal error modelingfor CNC machine tool[J]. Key Engineering Materials, 2009, 392: 30-34.
[19] Toshimichi, Moriwaki. Thermal Deformation and Its On-Line Compensation of Hydrostatically Supported Precision Spindle. CIRP Annals Manufacturing Technology, 1988, 37(1):393-396.
[20] K. Kim, M. Kim, S. Chung. Real-time Compensatory Control of Thermal Errors for High-speed Machine Tools[J] Proceedings of the I Mech E Part B Journal of Engineering Manufacture, 2004(218): 913-924.
[21] Z. Lin, J. Chang. The Building of Spindle Thermal Displacement Model of High Speed Machine Center[J]. International Journal of Advanced Manufacturing Technology, 2007, 34:556-566.
[22]杨建国,薛秉源. CNC车削中心热误差模态分析及鲁棒建模[J].中国工程机械,1998,9(5):31-35.
[23]李永祥.数控机床热误差建模新方法及其应用研究[D].上海:上海交通大学制造技术及自动化专业博士学位论文,2007.
[24]李永祥,童恒超,曹洪涛,等.数控机床热误差的时序分析法建模及其应用[J].四川大学学报,2006,38(2):74-78.
[25]鲁远栋.数控机床热误差检测及补偿技术研究[D].成都:西南交通大学机械制造及其自动化专业硕士学位论文,2007.
[26]邓三鹏.基于热误差补偿的加工中心在线检测软件的研究[J].机床和液压,2004,2:151-153.
[27] http://baike.baidu.com/view/2655944.htm
[28]王泽鹏. ANSYS12.0热力学有限元分析从入门到精通[M].北京:机械工业出版社,2010.
[29] E.Creighton, A.Honegger, A.Tulsian, D.Mukhopadhyay. Analysis of Thermal Errors in a High-speed Micro-milling Spindle. International Journal of Machine Tools and Manufacture, 2010, 50 (4):386-393.
[30]曹骏,胡佩俊,应济.基于接触热阻的主轴热特性有限元分析[J].机电工程,2008,25(2):20-22.
[31] Zhao Haitao, Yang Jianguo, Shen Jinhua. Simulation of Thermal Behavior of CNC Machine Tool Spindle[J]. International Journal of Machine Tools and Manufacture, 2007, 47(6):1003-1010.
[32]马晓波. SYSK-209型管子车丝机主轴箱热特性研究[D].长春:吉林大学机械制造及其自动化专业硕士学位论文,2006.
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