非接触式表面粗糙度识别方法的研究

提出了一种机加工纹理非接触式表面粗糙度识别的方法。该方法用纹理周期度来描述机加工纹理的表面粗糙度,通过采集表面粗糙度标准样块的图像,用图像处理方法提取相应的纹理特征值(如纹理周期度)存入数据库,再用同样的方法获取未知粗糙度等级的零件表面图像的纹理周期特征值,并与库中粗糙度标准样块图像的纹理周期特征值进行比较,按照最近似的原则得到所求表面的粗糙度。该方法识别精度较高,具有对光照条件不同的免疫力。     

基于小波包变换和奇异值分解的机加工表面纹理特征提取

为提取机加工表面的纹理特征,提出利用小波包变换和奇异值分解提取灰度图像特征的新方法,给出了小波包变换算法及奇异值分解算法,依据矩阵奇异值特征向量的均值和方差分别定义了灰度图像的特征参数k1和k2,并探讨了特征参数与表面纹理之间的关系。结果表明:特征参数能够敏感地反映机加工表面的纹理特征。k1表征了机加工表面的支撑面积,其值越大,支撑面积越大;k2表征了机加工表面纹理的粗糙度,其值越大,纹理越粗糙。因此,机加工表面的纹理特征可通过灰度图像特征参数k1和k2评定。     

基于加工纹理平均方向的表面缺陷检测

针对机加工零件表面划痕缺陷高精度、高效率的检测要求,提出了一种基于零件表面加工纹理平均方向的检测方案.利用零件图像与其均值模糊图像生成差分图像,采用阈值和形态学方法获得强化的纹理;采用最小外接矩形从中提取主干纹理,利用统计方法和两次平均方法计算纹理的主方向,利用纹理的方向偏差检出异常纹理.实验结果表明,该方案能实现单组...     

基于SFS技术的纹理力触觉再现方法研究

虚拟现实技术中,纹理的力触觉表达通常需要提取纹理表面的高度轮廓特征,从而再现纹理的凹凸感,而图像纹理则反映的是纹理表面的二维灰度特征.提出了一种根据图像灰度信息恢复表面三维轮廓(shape from shading,SFS),并用于纹理的力触觉表达的方法.采用Tsai & Shah算法从二维纹理图像中恢复出表面三维微观形状,并用力触觉模型渲染.该方法无需专门仪器测量物体表面的微观轮廓,无需设计专用的纹理力触觉表达装置.实验表明该方法是可行的,并通过对实验结果的分析给出了改进方向.     

毛刺缸套的成因探讨

目前，大量汽车车型采用全铝发动机，而作为发动机的重要部件——铝缸体，一般都需镶铸铁缸套来提高缸筒的耐磨性，这些缸套称为铸入式缸套。而作为缸套与铸铝发动机体的结合表面有两种形式：一种是通过机加工形成的螺纹状表面；另一种是控制峰高和谷深的铸态纹理表面，把这种具有一定峰高和谷深的铸态纹理表面的缸套称为毛刺缸套。     

齿轮滚磨光整加工的理论分析及实验验证

提出了一种齿轮滚磨光整加工的技术方案,阐述了该工艺的加工机理,重点研究了滚抛磨块与工件表面间复杂的相对运动情况,建立了数学模型,推导出计算切削速度的公式,从理论上找到影响加工效果的主要因素,通过MATLAB软件分析各因素的影响规律;实验表明,通过该方法对齿轮进行光整后,齿面表面粗糙度Ra能从0.7μm左右降低到0.265μm,机加工后的表面纹理和表面微裂纹消失,有助于提高齿轮的寿命和较小运行噪音,为该工艺的进一步研究和工业应用提供了基础。     

铁谱磨粒形态分形特征参数提取方法研究

阐述了分形与分形维数的定义，给出了铁谱磨粒分形维数和无标度区间的计算原理。编制了磨粒图像处理及磨粒分维计算的计算程序，并以片状磨粒为实例，提取了该磨粒的轮廓分维特征、磨粒表面纹理特征、表面纹理方向特征与磨粒表面间隙度特征四个特征值，为有效识别磨粒提供科学依据。     

基于纹理分析的小波变换图像清晰度评价方法研究

验证分析了小波变换在图像清晰度评价上应用的可行性,研究发现基于小波变换的图像清晰度评价函数性能与图像的空间纹理分布有很大的关系,采用图像灰度梯度方向矩阵的纹理分析方法,可以显著提升其性能.由于机加工零件表面纹理的普遍存在,对此类图像进行纹理分析有了实际应用意义.在对图像纹理特征进行统计分析的基础上,本文提出了一种基于纹理分析的图像小波变换清晰度评价方法.经实验验证,此评价函数针对具有纹理特征的目标有优越的性能,具有较高的灵敏度和分辨力（优于2 μm）.     

不同机加工表面微观形貌的特征分析

以机加工标准样块为对象,研究了不同机加工表面形貌粗糙度的差异,分析了不同机加工获得表面形貌的特征,以及观察了同种机加工方法获得的不同粗糙度表面形貌。结果表明：各种机加工方法获得标准样块的表面形貌及其粗糙度值都存在着不同程度的差异;不同机加工表面形貌微细结构致密度和轮廓高度峰值都各不相同,这与其加工机制有关;同种机加工获得不同粗糙度的表面形貌结构具有自相似性,而且具有典型的形貌结构特征,可用于区分不同机加工方法。     

Gabor滤波器在自动视觉表面检测中的应用

提出一种基于Gabor滤波器的纹理表面缺陷检测方法。该方法基于Gabor滤波方案，计算纹理图像与某一Gabor滤波器卷积能量输出响应。选择Gabor滤波器的最优参数，采用简单的二值化技术将纹理差别转化为可检测的滤波器输出。纺织品、铣磨面等结构纹理和皮革、砂纸等随机纹理的实验结果证明了该方法在识别不可定量测量缺陷方面的有效性。     

轮对表面几何参量检测

文中介绍设计系统的要求与总体构思.从图像获取和图像处理的角度上,详述车轮表面质量各项参数的获取和处理.最后简要说明过程中出现的误差和问题及应该注意的问题.     

Effect of surface roughness and surface texture on scuffing

This paper discusses the results of disk tests designed to examine the effect of surface roughness and surface texture on scuffing and related behavior. AISI 9310 steel disk of varying surface roughness and surface texture, along with a MIL-L-7808G lubricant, were used. It is shown that, under otherwise comparable situations, (a) an increase in the composite surface roughness increases the coefficient of friction at scuffing, decreases the scuff failure load, and decreases the critical temperature, (b) the cross-ground disks give a lower coefficient of friction at scuffing and a higher scuff failure load than the circumferentially-ground disks, but nearly the same critical temperature, and (c) an increase in the sliding velocity or sum velocity, at a constant sliding-to-sum velocity ratio, decreases the coefficient of friction at scuffing, decreases the scuff failure load, and decreases the critical temperature.The superior performance of the cross-ground disks compared with the circumferentially-ground disks is attributed to the effect of surface texture on microelastohydrodynamic action. The variations of the oil film thickness ratio at scuffing, the coefficient of friction at scuffing, and the critical temperature with respect to surface roughness, surface texture, and operating variables have been shown to correlate well with a dimensionless parameter $\text{ξ}{}_{\mathrm{?}}$.     

具有复杂型面机架的快速曲面重构技术

零件的曲面模型是获得其逆向设计数据等后续处理的关键环节。为了快速获得具有复杂型面机架的设计数据,研究了该机架点云曲面重构的获取方法。鉴于机架不同部位对逆向设计精度要求不同,采用Imageware和Geomagic Studio软件对机架的销孔和外形点云分别进行曲面重构之后,再实施整个模型的曲面整合策略。介绍了应用两种软件完成机架曲面模型的主要处理过程及关键环节。该方法能快速获得符合精度要求的机架曲面模型,可行且高效,为机架曲面模型的实体化及其后续处理提供了可靠依据。     

Prediction of surface reconstruction uncertainties for freeform surface inspection

A method is introduced to predict uncertainties of the B-spline freeform surfaces that are reconstructed from the measurement points for inspection of freeform surfaces. The uncertainties of a reconstructed B-spline surface are modeled by variances of coordinates of points on this freeform surface. Prediction of the uncertainty at any location on the reconstructed B-spline surface is carried out in two steps: (1) estimation of variances of the B-spline surface’s control points introduced by the surface reconstruction process, and (2) propagation of the variances from the control points to the points on the B-spline freeform surface. In this research, the variances of the control points of the reconstructed B-spline surface in all three directions are considered to improve the accuracy of uncertainty prediction in the regions with significant changes of geometric shapes. Both the errors and uncertainties at different locations on the reconstructed surface are considered in freeform surface inspection to compare the manufactured surface against the design surface and its tolerance. The developed method has been applied to two case studies to demonstrate its effectiveness.     

Role of surface texture of harder surface on subsurface deformation

Plastic deformation and damage accumulation below the contact surfaces play an important role in sliding wear of ductile materials. In this study, metallographic techniques have been used to determine the extent of plastic deformation and strain localization events that occur at various depths beneath the worn surface in the subsurface zones of the ductile pins slid against harder plate with various surface textures. Results showed that the magnitude of plastic strain gradient and the depth of highly deformed zone correlate with coefficient of friction, which in turn depends on the surface texture of harder counterface, under both dry and lubricated conditions. It was also observed that the gradient of equivalent strain, as it approaches the worn surface, was higher under dry conditions when compared to that under lubricated conditions.     

表面分析仪器在超疏水表面研究中的应用

超疏水表面制备与研究是近年来材料科学的重要研究方向,超疏水表面的研究离不开表面分析测试仪器。本文简要介绍了超疏水材料的表面特性、理论模型及其制备方法,重点介绍了扫描电子显微镜、X射线光电子能谱、原子力显微镜和表面接触角测试等几种常用表面分析方法的基本原理及其在超疏水表面研究中的具体应用。     

A method for surface/surface intersection

A method for solving the problem of surface/surface intersection in suggested. This method uses an adaptive subdivision and a facetted model based on triangles. A bounding box and a different dividing method are newly developed. Instead of the calculation of the characteristic points, a new linking technique is developed. This method solves the intersection problem between bicubic or higher grade surfaces. The desired caculation-precision is specified by the input parameter.     

Effects of surface roughness and surface films on contact resistance

An analysis of the electrical contact resistance between two metals with a tarnish film was carried out assuming the asperities to be represented by randomly distributed cones with base angles which vary with the surface roughness, and assuming that the radius of the broken area of the film at the interface of each contact asperity is constant beyond a critical depth of penetration of an asperity.The validity of the proposed theory was confirmed by experimental data of the electrical contact resistance between a silver cone and a silver flat on which carbon films were deposited, and between a silver flat with an Ag₂S tarnish and a palladium flat without tarnish. Comparison of theoretical and experimental data shows that the critical depth of penetration U_e of an asperity varies mainly with the surface roughness, the thickness of the tarnish film and the amount of plastic deformation of the contact asperities with films, i.e.$\text{U}{}_{\mathrm{e}}\text{σ}\text{= kR}{}^{\mathrm{j}}{}_{\max }$, where R_max and σ are the maximum height and the standard deviation (r.m.s. roughness) of the profile ordinates, and j and k are constants dependent on the type of finish, the thickness of the film and the difference in the hardness of the mating surfaces.     

基于Rhino曲面设计的精简面研究

对现有Rhino软件建模方式的弊端进行分析,确定了若干问题出现的原因;然后提出精简面构建的基础理论;最后以实际项目的案例进行验证,从而总结出问题的解决方案。