【作者】 侯国安；

【导师】 孙涛；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 超精密加工技术在现代国防和高新技术中占有重要地位，超精密金刚石车床是实现超精密加工的重要设备。从加工的观点看，机床的作用是准确的控制刀具和工件之间的位置，机床加工时使刀具和工件之间按预定的轨迹运动，以获得所需要的工件表面。这需要超精密金刚石车床具有良好的动态性能。但是，由于机床各部分的连接刚度是有限的，机床加工时刀具刀尖和工件之间的振动是不可避免的。随着对加工精度的要求越来越高，机床本身的动态特性对加工精度的影响越来越突出。机床的结合面是影响机床动态特性的主要因素。相比普通机床，超精密机床的一大特点是大量采用流体静压支承，流体静压支承的油膜或气膜作为超精密机床的结合面，它们的性能是影响超精密机床动态特性的重要因素。因此，本文针对流体静压支承的性能及其对超精密金刚石车床动态特性的影响进行研究。首先，建立了考虑支撑面倾斜情况时液体静压导轨油腔流量公式和油膜厚度表达式，以此为基础建立了超精密金刚石车床液体静压导轨的有限元计算模型。根据该模型编制了计算程序，得到了导轨五自由度方向的刚度和角刚度，并对其影响因素进行了研究。在分析气体静压主轴和液体静压导轨异同的基础上建立了气体静压主轴的有限元模型，编制了计算程序，计算了主轴五自由度方向的刚度和角刚度，分析了其影响因素。分析了所设计的超精密机床的结构特征，依据拉格朗日方程建立了机床的动力学方程，并对建立机床动力学方程所需的参数进行了辨识。通过实验辨识了液体静压导轨和气体静压主轴各方向的刚度，验证了所建立的有限元模型的正确性。通过实验辨识了液体静压导轨和气体静压主轴各方向的阻尼。建立了直线电机直接驱动的液体静压导轨和分体式无框架力矩电机直接驱动的气体静压主轴的控制系统模型，仿真得到了控制系统的刚度。机床的动态特性用刀尖和工件之间的频率响应来表示。首先对机床进行了模态分析，求解得到了机床的固有频率和振型。然后通过刀尖和工件处的响应分析找出了对机床精度影响较大的固有频率和振型。研究了液体静压导轨和气体静压主轴的刚度、角刚度和阻尼等参数的变化对其机床动态特性的影响规律。为超精密机床的设计提供了理论依据。慢速刀具伺服加工和快速刀具伺服加工是超精密机床常用的独特加工工艺，因此，研究了慢速刀具伺服加工时液体静压导轨的运动特性，以及误差产生的原因和影响因素。建立了快速刀具伺服系统的动力学模型，分析了快刀加工时由于自身的高频振动引起的误差大小及其影响规律，为误差补偿提供了理论依据。最后，对超精密金刚石车床振动信号进行了测试，并开展了端面车削加工实验研究。通过机床振动信号的测试得出机床加工时刀尖与工件之间的振动频率，与理论计算得出的频率进行对比，验证了理论分析的正确性。对车削加工实验得到的表面进行功率谱密度分析，获得了工件表面形貌的空间频率成分，与机床振动相对照，揭示了机床振动频率与工件表面形貌空间频率之间的关系。采用功率谱密度与二维小波变换相结合的方法提取出车削加工表面上特定空间频率成分的三维表面形貌，计算得到了这些特定空间频率成分对原始表面形貌的影响程度。更多还原

【Abstract】 Ultra-precision machining technology plays an important role in the modernnational defense system and high-tech field. Ultra-precision diamond lathe are keyequipments to achieve ultra-precision machining. Based on the viewpoint ofprocessing, the function of a machine tool is to accurately control the positionbetween the tool and workpiece. So an ultra-precision machine tool has to meet thefollowing requirements: high dynamic stiffness. However, due to the stiffnesses ofconnections between parts in the machine are limited, the vibration between tool tipand workpiece is inevitable in machining. Conection surfaces of an ultra-precisonmachine tool are the primary factors influencing dynamic performances of themachine. Contrast to general machine tools, the major feature of an ultra-precisionmachine tool is with hydrostatic supports. Performances of hydrostatic supports aredominating factors to affect the dynamic characteristics of an ultra-precisionmachine tool. This paper studies the performance of hydrostatic bearing and itsinfluence on ultra-precision diamond lathe dynamic characteristics.First, create the oil chamber flow formulas and film thickness expressions,consider hydrostatic guideway a support surface inclined, as a basis, establishfor theultra-precision diamond lathe hydrostatic guideway finite element model. Accordingto the model, developed a computer program calculated the stiffness and angularstiffness of five degrees of freedom direction of the slide, and its influencing factorswere studied. A finite element model of the spindle is established, on the basis ofanalysis similarities and differences of aerostatic spindle and hydrostatic guideway.An FEA program have been written to accurately calculate the stiffness and angularstiffness of the spindle in the direction of five degrees of freedom respectively, andits influencing factors were studied.One more accurate ultra-precision machine tool dynmics model has been found.Stiffnesses and dammpings of the hydrostatic rails and the aerostatic spindle areidentified by model experiments. Experimental results agrees well with thetheoretical calculation, proving the correctness of the finite element model. Acontrol system model has been built, which features the direct-driven linear motorand hydrostatic rails. Similarly, a control system, combing the brushless torquemotor and aeostatic bearings, is also established. Stiffnesses of control systems aresimulated respectively. Based on the results above, an ultra-precision diamond lathedynamic model has been achieved according to the Lagrange equation.Machine tool dynamic performace is featured by frequency response betweenthe tool nose and workpiece. Firstly, one mode analysis of the designed ultra- precision machine tool is done to obtain natural frequencies and mode shapes of themachine tool. Next, a response analysis is implemented to identify whichfrequency and mode shape have more impact on the machine accuracy. Influences ofthe stiffness， angular stiffness and damping of hydrostatic guideways on theultra-precision machine tool dynamic performance are investigated respectively.What’s more, the impacts of spindle stiffness, angular stiffness and damping on themachine tool dynamic characteristics are also investigated. All these work give clueson an ultra-precision machine tool design. At last, an mode experiment is done toverify the reliability of theoretical analysies. Slow tool servo technology and fasttool serveo technology are two common processes exploiting at an ultra-precisionmachine tool. So, in this paper, specialties of the slow slide servo maching areanalysed. Moreover, motion errors of hydrostatic guideway in the process of slowslide servo machining are reaserched. The reasons of motion errors and thoseinfluencing factors are studied respectively. A fast tool servo dynamics model hasbeen established. An analysis probes into the influence of high frequency vibrationon the machining accuracy in fast tool servo process, which uncovers the factorsdecrease the machining accuracy and provides a theoretical basis for the errorcompensation.Finally, the ultra-precision diamond lathe vibration signal are detected, andconducted face turning experimental study. Obtained the vibration frequencybetween the workpiece and tool tip through the vibration signal detection,comparing the theoretical calculated frequency and the theoretical analysis is correct.Power spectral density analysis of the experiment turning surface is conducted,obtained spatial frequency components of the surface topography, in contrast withthe machine vibration, reveal the relationship of vibration frequency of the machineand the spatial frequency of workpiece surface morphology. To extract thethree-dimensional surface topography of specific spatial frequency components onthe machining surface, make use of the method of combining power spectral densityand dimensional wavelet transform. calculated the degree of influence of thesespecific spatial frequency components for the original surface morphology,revealing the relationship between the machine vibration and the surfacemorphology.更多还原