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超精密直线度测量及表面微观形貌分析研究

Research on Ultra-Precision Measuring Straightness and Surface Microtopography Analysis

【作者】 尹自强

【导师】 李圣怡;

【作者基本信息】 国防科学技术大学 , 机械电子工程, 2003, 博士

【摘要】 超精密加工是现代先进制造技术一个重要组成部分,同时超精密加工又是一项复杂的多学科综合的高级技术,涉及的范围包括加工方法、被加工材料、加工设备、工艺手段、检测方法、环境因素以及操作人员的技艺水平等。本论文以超精密加工中的直线度检测技术与超精密加工表面形成的仿真建模、特征分析及其误差辨识为主要研究内容,具体对如下几个方面进行了研究: 1.超精密直线度的测量方法。在超精密加工中,常用来测量直线度的扫描测头法有两点法、三点法以及扫描测头加角度检测仪的混合检测方法,并且需要采用误差分离的方法将工件直线度与溜板直线运动误差分离出来,当溜板的偏摆误差不可忽略时,还需采取一定的措施将其分离出来。本论文提出一种新的采用自准直仪加扫描测头的混合检测方法可高精度地测量工件的直线度轮廓,从而也可分离出溜板的直线运动精度。 2.超精密工件直线度精确重构理论。已有的基于扫描测头法的误差分离技术在当采样间隔小于传感器间距的情况下都是一种近似的或逼近的算法,并且大多基于某种假设的“先验”条件或仅适应某些有一定要求轮廓的测量,不能精确重构出任意被测工件的直线度轮廓。本论文基于差分测量数据,在频域与时域范围分别提出了两种精确重构算法,完美地解决了近二十多年来国内外在该领域研究的问题,将直线度测量的研究推到了一个新的高点。同时这两种精确重构算法均可以应用于剪切干涉的测量,从而赋予剪切干涉测量以新的竞争力,也解决了国内外长久以来对剪切干涉测量重构算法的研究问题。 3.超精密车削工件表面形貌形成的仿真建模技术。基于机床运动学和切削理论对单点金刚石加工时的工件端面切削及“飞切”加工进行了仿真建模。解决了现有文献中建模算法的不足之处。采用该模型可以模拟刀具切削运动的轨迹、预测工件表面三维微观形貌及二维截面轮廓形状等表面特征,指导实际的加工操作,减少盲目“试切”加工的花费。 4.工件表面形貌特征的分析。在考虑振动频率与主轴旋转频率之比以及刀具干涉现象对工件表面微观形貌特征的影响的基础上,比较全面地分析了工件三维表面形貌的特征。并采用傅立叶分析技术分别沿工件表面径向、周向与螺旋方向对其频率特征进行理论分析,考虑了各种因素对截面轮廓特征的影响情况。 5.误差辨识方法。基于工件表面三维形貌的建模对刀具与工件间存在的相对振动进行了辨识,从理论上解决了相对振动辨识的研究问题。并提出了可以辨识振动频率的两种方法,即沿工件径向周向截面的特征分析法和沿工件螺旋截面的特征分析法。

【Abstract】 Ultra-precision machining is an important factor of advanced manufacturing technology, on the other hand, it is a complex advanced technology synthesized many techniques which involve machining methods, material, machining tools, technics, measuring methods, environment , arts of operators and so on. The mainbody of this dissertation are measuring method for ultra-precision straightness, modeling the surface topography of ultra-precision turning, analyzing the characteristic of workpiece surface and error identification. Its contents include several aspects as follows.1. Measuring methods of ultra-precision straightness. Some scanning probe methods which include two points method, three points method and the mixed method which employs two scanning probes and one angle probe, and the errors separation methods which can separate workpiece straightness from straightness motion error of the scanning stage are used in precision machining widely. Some methods are needed to be adopted to separate the yaw error of scanning stage when it can’t be ignored. This dissertation bring forward a novel method which employs autocollimation and scanning probes. The straightness profile of workpiece can be measured, and the straightness motion errors of scanning stage can be separated precisely.2. The exact reconstruction theory of ultra-precision workpiece straightness. The existing error separation technology based on scanning probe method are all approximate arithmetic, and mostly assume a priori knowledge or only adapt to measuring some special profiles. For more than 20 years, some methods have been developed for these cases of difference measurements, but all these methods cannot exact reconstruct straightness of arbitrary workpiece. This dissertation suggests two methods are named frequency domain method and time domain method. Both can solve this problem. Besides being applied in measuring straightness, these two exact reconstruction methods also can be applied in shearing interferometry. As a consequence, shearing interferometry can hope to compete with the established interferometric methods based on the use of a reference wave.3. The technology of surface topography modeling and simulation for ultra-precision diamond turning. Based on machine kinematics and cutting theories, the simulating method for the generation of three-dimensional surfaces in face turning and flycutting of SPDT is studied. Some problems existing in literature are solved. The model can be used for simulating the locus of tool motion, predicting the surface topography and the characteristic of section profile, and this simulating model also can help to determine the optimal cutting conditions without the need for costly trial-and-error cutting tests.4. Analyzing the characteristic of workpiece surface. Taking into account the ratio between the relative tool-workpiece vibration frequency and the spindle rotating frequency, the phenomena of tool interference, this dissertation analyzes the characteristic of workpiece surface topography more completely. And various factorswhich affect the characteristic of section profile are considered. The frequency characteristics of radial, circumferential and spiral section profile are analyzed in theory using Fourier transforms.5. The method of error identification. Based on the model of surface topography, this dissertation solves the problem of identifying the frequency of relative tool-workpiece vibration in theory. Two methods of spiral and radial-circumferential analysis using surface data are proposed.

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