三维表面粗糙度参数的矩表征

以分形几何理论为基础,利用轮廓谱矩和表面谱矩对三维表面粗糙度评定参数进行了分形表征;并且从理论上提出了一些新的三维评定参数,如均一性、等方性等;最后还进行了实验验证。     

录像带的表面形貌和微摩擦特性

利用原子力／摩擦力显微镜研究了Ｓｏｎｙ和国产画王录像带的表面形貌、纳米级载荷下的微摩擦性能。结果表明：画王带的粗糙度和粒度均与Ｓｏｎｙ带相当，但其摩擦系数高于Ｓｏｎｙ带；摩擦力图与表面形貌、形貌斜率图间有较好的对应关系，微摩擦力随载荷、表面形貌斜率的增加而线性增大。     

溅射超薄Au膜表面形貌的分形表征

采用直流磁控溅射技术制备超薄Au膜,用原子力显微镜观察薄膜的表面形貌。功率谱密度计算结果显示,随着溅射时间增加,高频段曲线拟合直线的斜率增大,相应的分形维数从2.579减小到2.500;而低频段曲线拟合直线的斜率减小,相应的分形维数由2.607增大到2.819,薄膜表面形貌存在多尺度行为。多重分形谱结果表明,随着溅射时间的增加,分形谱宽Δα从0.051增大到0.118,说明薄膜表面高度分布范围愈来愈宽,表面粗糙度愈来愈大,与rms研究结果一致。样品的Δf均0,说明样品表面最高峰位的数目均多于最低谷位的数目。     

双分形表面的粗糙度表征及参数计算

通过对精车和磨削加工不锈钢表面的粗糙度测量，发现它们的轮廓功率谱在其谱区内均服从两种不同的幂定律。本文对这种双分形表面提出了一种新的表征方法。并给出了分形参数的计算公式。实验表明，加工方法越精细，其边界频率越高，表面长度尺度越小。     

粗糙表面轮廓的非高斯AR模型双谱估计

介绍了双谱估计的参数模型法 ,由AR(AutoRegression)模型参数估计粗糙工程表面的非高斯轮廓的双谱。通过对几种典型加工表面 ,分别采用经典双谱估计和参数模型法双谱估计后认为 ,即使在测量数据较少的情况下 ,参数化模型法仍能提供高分辨率的双谱估计精度和有效的相位信息 ,能较好地反映粗糙表面轮廓高度的偏斜分布程度。     

先进陶瓷材料超声振动铣磨加工表面粗糙度仿真及实验(英文)

为了对超声振动铣磨加工先进陶瓷的表面粗糙度进行预测,建立了加工表面形貌的仿真模型.通过实验测得砂轮表面形貌和磨粒突出高度信息,并对这些信息进行Kolmogorov-Smirnov正态验证,发现砂轮表面形貌不服从高斯分布.对非高斯分布的数据进行Johnson变换,建立砂轮形貌的数值模型.结合砂轮表面形貌和磨粒与工件的相对运动分析,提出了一种表面轮廓搜索方法,进而生成了加工表面的三维形貌.最后,在DMG ULTRASONIC 70-5 linear机床上进行切削实验,对仿真结果进行了验证,结果表明仿真与实验结果具有较好的一致性,并对仿真误差产生的原因进行了分析.     

采用分区法提高数控三坐标曲面投影加工的精度

零件加工后表面残留高度不均匀的现象一直是数控曲面加工中亟待解决的问题之一.本文分析了数控三坐标曲面加工行距计算公式,得出了曲面数控投影加工行距与曲率半径的关系.结果表明,曲面曲率半径和曲面截面线加工点处斜率参数对基于CAD/CAM的复杂曲面数控三坐标投影加工误差十分敏感.斜率大的区域因原有走刀行距的过度拉伸而产生严重的欠切现象,使被加工曲面出现明显的残留面.针对这一情况,提出了一种刀具轨迹密化的方--分区域投影加工.该方法的特点是对曲面截面线加工点处斜率参数和曲面曲率半径小的区域,减小行距,并进行刀具轨迹编辑,从而使刀具轨迹的刀位达到密化,改善了残留高度的不均匀状况,提高了曲面加工精度.     

三维表面微观形貌的二维功率谱表征

二维谱分析在工程表面的研究中是有效和实用的，在介绍二维快速傅里叶变换基本概念的基础上，推导出了二维功率谱、角谱和半径谱在三维表面形貌中的应用计算方法，并对一些有代表性的精加工表面试件进行了实验研究。结论表明，二维谱分析技术可以表征表面纹理的方向性和不同波长对表面粗糙度高度均方根的影响。     

表面计量中触针式仪器的若干进展(英文)

在表面测量中,对于触针式仪器需求相当大,因为触测法对斜率不敏感,测量结果具有高度的逼真性,这使它适用于测量同时含有形状与纹理参数的复杂物体.但是由于它测量速度相对较慢,在某些场合会形成劣势.本文阐明可以通过优化阻尼因数来提高横向移动速度,通过建立能够确定触针是否承受过压的判据,使触针不会引起表面损伤.     

采用分区法提高数控三坐标曲线投影加工的精度

零件加工后表面残留高度不均匀的现象一直是数控曲面加工中亟待解决的问题之一．本文分析了数控三坐标曲面加工行距计算公式，得出了曲面数控投影加工行距与曲率半径的关系．结果表明，曲面曲率半径和曲面截面线加工点处斜率参数对基于CAD／CAM的复杂曲面数控三坐标投影加工误差十分敏感，斜率大的区域因原有走刀行距的过度拉伸而产生严重的欠切现象，使被加工曲面出现明显的残留面．针对这一情况，提出了一种刀具轨迹密化的方——分区域投影加工，该方法的特点是对曲面截面线加工点处斜率参数和曲面曲率半径小的区域．减小行距，并进行刀具轨迹编辑，从而使刀具轨迹的刀位达到密化，改善了残留高度的不均匀状况，提高了曲面加工精度．     

基于分形和小波的几何型面加工误差综合分析

对几何型面加工误差提出并建立了基于分形和小波的综合分析方法，可以精细分析几何型面加工误差的微细成分，并重构出型面轮廓加工误差曲线，以便进行公差与性能关系分析以及加工过程质量监控等相关工作。应用实例表明，该方法是非常有效的。     

Experimental Investigation of Thermal Contact Conductance: Variations of Surface Microhardness and Roughness

Surface roughness parameters were measured using nine different sampling intervals. The results showed that the roughness of profile was nearly a constant at all sampling intervals; the slope, peak curvature and density of the profile decreased with increasing sampling interval; and the distribution of the peak height was different from the profile height distribution and was not Gaussian. It was found that the surface microhardness value, under small loads, varied with the indentation size and the surface preparation procedure. A model was developed which used a discretization method to obtain the contact radius and area in each section of the surface summit height distribution curve. This model eliminated some of the assumptions made by previous models and can be used to predict the thermal contact conductance without assuming the asperity deformation mode and surface summit height distribution. The predicted thermal contact conductance values were in good agreement with experimental results.     

碳/碳复合材料切削表面粗糙度的评定方法及评定参数研究

通过对航空航天领域应用的碳，碳（C／C）复合材料和硬铝材料切削表面进行三维表面粗糙度测量实验，研究了C／C复合材料切削表面粗糙度的二维评定与三维评定方法、幅度表征参数及分形表征。结果表明：对于C／C一类的复合材料需选用三维评定参数才能准确表达其切削表面粗糙度的真实特征；表面均方根偏差比表面算术平均偏差更适合作为C／C复合材料切削表面粗糙度的幅度评定参数，表面粗糙度的三维标准应优先选用表面均方根偏差作为评定参数；表面分形维数可作为C／C复合材料切削表面粗糙度的表征参数之一。     

无氧铜超精加工表面微观形貌的分形维数表征

单点金刚石超精密加工能够获得纳米级的低粗糙度表面。进一步的实验表明,采用该工艺进行退火态无氧铜切削,已加工表面在刀痕基础上还会出现清晰的晶界浮凸现象。传统的粗糙度概念无法有效表征与区分含有晶界浮凸信息的超精加工表面微观形貌。引入分形维数概念,采用该理论中尺码法对无氧铜超精加工表面的微观形貌进行分形维数计算;为降低切削刀痕信号干扰、突出晶界浮凸信息,设计表面信号带阻滤波方法。计算结果表明,超精加工后的表面分形维数包含了加工刀痕与晶界浮凸信息,由于两者尺度相近,传统的粗糙度测量无法区分其差异;采用带阻滤波与尺码法耦合方式,能够有效识别晶界浮凸特点,定量地反映微观尺度下超精加工表面的形貌特征信息。     

Surface roughness evaluation via ultrasonic scanning

Despite extensive applications of ultrasonic waves to various nondestructive testing and evaluation of materials, scattering of focused ultrasonic waves due to surface roughness has not been fully investigated. This paper presents an analytical and experimental evaluation of surface roughness measurement using focused ultrasonic beams. The characteristics of focused ultrasonic waves are analyzed by using the impulse response method with a sine-modulated Gaussian pulse as source. First, the beam profile in the focal plane of the focused ultrasonic transducer is analyzed both numerically and experimentally. Second, peak amplitude distribution and reflected waveforms from a flat surface with various incident angles are analytically generated and compared with experimental results. Then, the peak amplitudes of the ultrasonic waves reflected from cusped surfaces which are easily found among machined surfaces are analyzed and compared with experimental data for the first time. The analysis shows good agreement between analytical and experimental results. The excellent correlation between the measurements using a profilometer and the proposed ultrasonic system demonstrates a good potential for surface roughness measurement by ultrasonic sensing.     

Cusp geometry analysis in free-form surface machining

The measurement of cusp height is the conventional method for determining the amount of excess material on free-form machined surfaces, and is frequently used to justify surface quality at the design and manufacturing stages. Although, such surface assessment strategies are generally accepted by manufacturers and customers, they may not provide enough information to qualify the machined surfaces. The aim of this work is to develop a new surface assessment method, for the machined surfaces by determining the area and the volume of the cusps. The method is built on analytic mathematical models of the surfaces and enhanced by the explicit forms of the cusp area and volume equations. The accuracy and reliability of these analytical formulations have been tested with data from machining trials and comparisons with a commerical software package. The indications are that this new approach offers a more comprehensive surface assessment strategy than the conventional measuring method.     

Studies on the surface of high-performance alloys machined by micro-EDM

Micro-electrical discharge machining (EDM) is used in the fabrication of Ti-6Al-4V, SUS304, and SKH59 alloys, which are important aviation materials. EDM influences the surface morphologies of these materials and directly affects their reliability during use. However, current research focusing on the morphology of surfaces machined by micro-EDM is rare. Traditional surface evaluation parameter such as R_a cannot describe the surface morphology machined by micro-EDM precisely. Therefore, systematic research on surface morphology of the aforementioned alloys is presented in the study. Based on a novel evaluation method combining fractal theory with wavelet filters, first, comparative experiments on surface morphology evaluations of different materials were conducted and discussed. Second, two different pulse power supplies were studied to explore the effect of pulse power on the high-performance alloy surface. Third, three different micro-EDM processing methods were compared to study their effects on the surfaces of high-performance alloys. Finally, different machining parameters such as discharging energies, rotation speeds of the tool electrode, and gap voltages were set to investigate their effects on the surface morphology. The results showed that different materials, pulse power supplies, processing methods, and machining parameters greatly influence the surface morphology quality, and appropriate machining advice is proposed.     

接触传热表面粗糙度曲线的统计特征

测量了一般机械加工表面的轮廓曲线，基于小波变换提取了粗糙度曲线，分析了轮廓高度和接触峰高度的统计分布特征。研究结果表明，轮廓高度不服从严格的正态分布，但具有一定的正态性，而接触峰高度的统计特征与其评定标准有直接的关系。因此，对于接触热阻的计算模型来说，接触点数的计算应以合理选取接触峰的评定标准为前提。     

The use of diamond-tipped scanning tunneling microscope to study structural features of ta-C film

A physicomathematical modeling of the surface of a diamond-like carbon (ta-C) film is performed for the sp²/sp³ phase transition region, and results of scanning tunneling microscopic examination using a boron-doped single-crystal semiconductor diamond tip are provided. It is demonstrated that the height difference in the sp²/sp³ interface layer is not related to functional features of the tunneling microscope. A fractal analysis of the surface, contour, and profile of the section has been carried out by three independent methods; and the findings confirm that the surface belongs to the category of fractal Browning surfaces. It is shown that the real surface area under study can greatly exceed the area of the visible contact window.     

Laterally chromatically dispersed, spectrally encoded interferometer

We present a single-shot line sensor based on spectral interferometry. Light of a broadband laser source is chromatically dispersed by a grating and focused onto a line on the surface such that each focal point on this line is formed by another wavelength. The entire height profile is obtained by applying a phase evaluation algorithm to the registered interference signal, followed by a model-based approach. The sensor concept is finally verified by experimental results.