接触式与非接触式测量粗糙度方法探讨

就接触式与非接触式的材料表面粗糙度测量方法进行讨论，利用触针式表面形貌仪和白光干涉仪对6种不同粗糙度的标准样块进行了表面粗糙度测量。分析了两种测量方法的原理及其优缺点，其中接触式测量方法具有测量数据稳定、操作简单、测量范围大的特点，但有局限性。而非接触测量方法可以弥补接触式测量方法的不足，具有无损伤、精度高、速度快的特点。对比发现，对于6种标准样块而言，触针式表面形貌仪与白光干涉仪测量结果相近，白光干涉仪测量结果略高于触针式表面形貌仪，但均符合测量要求(示值误差不大于5%)。     

压电式粗糙度仪的频率特性测试研究

压电式粗糙度仪是一种常用的粗糙度测量仪器,可用于检测各种不同材料表面的粗糙度特征。与接触型粗糙度测量仪相比,压电式粗糙度仪具有许多优点,如非接触式测量、高精度、可重复性高等。但与另一种接触型粗糙度仪——电感式粗糙度仪进行特性对比会发现：压电式粗糙度仪低频特性差,因此,在使用之前,进行频率特性的测量非常重要。介绍了两种频率特性测量方法,并通过实验得到良好的数据支持,对压电式粗糙度仪的性能分析有重要意义。     

小样本磨削表面粗糙度测量方法研究

基于机器视觉的表面粗糙度测量方法主要通过图像特征信息与粗糙度的关联指标建立预测模型,但是样本量不足往往难以训练出有效的模型,导致测量准确率较低。针对以上问题,提出一种小样本磨削表面粗糙度测量方法。建立图像采集系统,采集不同粗糙度等级磨削表面图像作为原始样本;通过虚拟样本生成算法扩充样本量,采用灰度共生矩阵提取样本纹理特征;最后,通过神经网络建立预测模型。试验结果表明：样本量扩充后,表面粗糙度测量的准确率从80.4%提升到97.2%,证明了此方法的可行性,为小样本磨削表面粗糙度在机检测提供理论基础。     

基于化学蚀刻检测光学玻璃亚表面损伤深度

目的 提出一种光学玻璃机械加工亚表面损伤深度的检测方法,给光学玻璃超精密抛光的加工深度提供参考依据。方法 首先通过实验分析K9玻璃研磨试样在化学蚀刻过程中亚表面裂纹的结构变化,采用探针式粗糙度仪检测化学蚀刻表面的裂纹深度,并探讨探针半径和化学蚀刻时间对裂纹深度测量结果的影响,建立以蚀刻表面峰谷粗糙度(PV)表征亚表面裂纹深度的测量条件。然后利用激光共聚焦显微镜检测化学蚀刻表面PV粗糙度,确定光学玻璃的亚表面裂纹深度。最后采用截面抛光法直接检测光学玻璃的亚表面裂纹深度,验证上述两种检测方法的可靠性。结果 以蚀刻表面PV粗糙度表征亚表面裂纹深度的测量条件为,测量介质须在蚀刻表面裂纹开始融合之前有效探测至裂纹底部。针对W18和W40磨粒研磨的K9玻璃试样,采用激光共聚焦显微镜检测蚀刻表面PV粗糙度方法测得的两种试样裂纹深度为12.82 μm和20.45 μm,直接测量方法的测量结果为12.50 μm和19.34 μm。两种方法测量结果的偏差分别为2.56%和5.74%,一致性较好。结论 基于化学蚀刻和激光共聚焦显微镜检测光学玻璃亚表面损伤深度的方法不受表面裂纹宽度限制,满足以蚀刻表面PV粗糙度表征亚表面损伤深度的测量条件,且对试样损伤较小,提高了光学玻璃亚表面损伤深度的测量效率和结果可靠性。     

基于激光三角法的零件表面粗糙度在线测量

介绍一种零件表面粗糙度的激光在线测量系统,该系统基于激光三角测量系统,用无衍射激光光束作光源,用高精度的CCD摄像机作位移传感器,通过计算机进行数据处理得到表面粗糙度值。以车削表面为例,用触针法测得的表面粗糙度值和用该系统测得的表面粗糙度值相近,说明实现表面粗糙度在线检测是可能的,该测量方法具有测量速度快和能够显示被测表面的具体形貌等优点。     

引入迁移学习的铣削表面粗糙度评估北大核心

目前,许多基于机器视觉的粗糙度测量方法依赖特征指标无法准确地表达工件表面的粗糙度信息;而基于深度神经网络的测量方法,对工件图像的数量需求大,且要求所有图像均服从同一数据分布。针对上述方法的不足,在深度神经网路的基础上,引入迁移学习算法,提出了一种新的铣削表面粗糙度等级评估模型。它避免了人为设计特征指标所带来的主观因素影响,能自动提取工件图像中与粗糙度相关的特征。同时,该方法在提取特征的过程中,还考虑到了获得的图像数据分布不一定一致,有意识地去缩小数据分布的差异。实验结果表明,基于迁移学习的铣削表面粗糙度等级评估模型在各种光照不同的测量环境中,达到了99.3%的平均评估准确率,高于其它几种用作对比的评估模型。     

珩磨过程中非接触式主动检测系统

在珩磨加工中使用各种不同的主动检测系统,主要有接触式和非接触式两种。接触式测量方法具有许多不足之处,其中主要是接触头部的磨损,如果把测量装置放置在珩磨头里,那么这种磨损情况就会特别严重。此外,该系统还应该具有向发送器传递的环节,于是使它的结构就显得相当复杂。非接触式的测量方法是比较完善的一种方法,它可以消除由于测量头接触面的磨损,机器的振动、受力及热变形所引起的误差。 非接触式的气动方法在加工过程中的测量工作是由装在珩磨头内的喷嘴来进行的,向喷嘴供以高压的压缩空气。类似这样的系统是由苏联斯捷尔里达曼克斯基列宁机床厂和西德拿盖立公司设计的,然而它们的测量     

塑性加工摩擦学研究的新方法——三维表面形貌分析

确定金属表面的粗糙度和结构是塑性加工摩擦学研究中的重要内容,但以往使用接触式粗糙度促进行测量的方法有很大局限性,目前国外已采用三维表面分析的方法进行测量和研究,本文介绍了三维表面分析原理、设备、主要特征参数、对表面的分析实例及其特点,使读者对这一新技术有一全面的了解。     

基于视觉技术的三维曲面非接触无损检测方法

不规则自由曲面在机械工程中有着广泛的应用,对其进行三维无损检测是近年来国内外研究的热点问题之一,传统的接触式测量方法由于采用接触式测头,所以极易损坏待测表面,且难以测量弹性实体,测量效量差。提出了一种基于主动双目视觉传感技术的三维曲面非接触无损检测方法,通过向待测曲面投影特定结构光并接收反馈信息实现曲面三维坐标的快速高效检测。这种方法无须接触式测头,仪器小巧,测量仪器与被测件间无测量力,因而易于实现现场无损检测。分析了基于该方法的数学模型,并给出了计算机仿真实验结果。仿真实验证明,该方法能够实现三维曲面的高精度现场检测。     

膜式燃气表阀盖密封性检测研究

膜式燃气表是一种应用广泛的燃气计量仪表,燃气表中阀盖与阀座是构成其计量误差的主要因素,而表面粗糙度大小决定着气阀密封性能的好坏。分析了非接触方法测量表面粗糙度方案,发现光谱共焦法更适合阀盖的表面粗糙度测量;利用光谱共焦法对二维气浮平台上的阀盖进行表面粗糙度测量,测量结果与采用东京精密公司生产的触针式粗糙度仪测量值相比,存在较小误差。研究结果表明了光谱共焦法测量燃气表阀盖表面粗糙度的可行性,为定量检测阀盖工作面密封性提供了有效手段。     

Surface roughness measurement on machined surfaces using angular speckle correlation

Surface roughness is of great importance in fields, such as tribology, semiconductor technology and medicine. Stylus techniques, in which a stylus is drawn along the surface and the vertical movement of the stylus is recorded, have been used traditionally in measuring surface roughness. Non-contact methods, such as optical ones, have the advantage that they can be used for the in-process measurement of surface roughness. In this paper, results of the measurement of surface roughness using angular speckle-correlation on machined surfaces are presented. Surfaces of approximately 1.6 < R_a < 6.3 μm have been measured, the surfaces being classified in the same manner as when using a stylus instrument. ASC is a technique that also allows in-process measurement of the roughness of surfaces on machined surfaces. A new technique to achieve increased repeatability by using an angle detection unit is also presented in this paper.     

Progress in fluidized bed assisted abrasive jet machining (FB-AJM): Internal polishing of aluminium tubes

This paper deals with the internal finishing of tubular components made from a high strength aluminium alloy (AA 6082 T6) using a fluidized bed assisted abrasive jet machining (FB-AJM) system.Firstly, a Taguchi's experimental plan was used to investigate the influence of abrasive jet speed, machining cycle, and abrasive mesh size on surface roughness and material removal trends. Secondly, the leading finishing mechanisms were studied using combined 3d profilometer-SEM analysis to monitor the evolution of the surface morphology of machined workpieces. Finally, the circumferential uniformity and precision machining of the inner surface of workpieces were tested by evaluating the values of the more significant roughness parameters in different circumferential locations.Consistent trends of surface roughness vs. operational parameters were measured, and significant material removal was found to affect the workpieces during machining. As a result, FB-AJM was found to preferentially machine the asperities and irregularities of the surface, thereby altering the overall surface morphology producing more regular and smoother finishing. Moreover, the good circumferential uniformity and machining accuracy FB-AJM guarantees even on ductile aluminium alloy workpieces ensure that this technology can be applied to a diverse set of industrial components.     

Control of contact stiffness in machine parts

Rigidity is one of the main factors decisive for the quality of machine tools, measuring instruments and many other devices. One of the principal deformation components of a machine element is contact deformation due to surface roughness. The contact rigidity can be controlled by selecting appropriate working methods and parameters, influencing directly the surface roughness characteristics. It is for this reason that many theoretical and experimental works have been devoted to the problem mentioned. As a result of the first load being applied the surface roughness undergoes elastic-plastic deformation, which has not yet been described by any consistent theory. During unloading and subsequent loading processes the deformed asperities remain elastic (if there are no tangential displacements). However, as a result of no data being available as regards the stereometric features (3-D) of roughness and their changes due to plastic deformation, the theoretical results are charged with considerable errors. In engineering problems the value of a contact deformation may be computed making use of statistical relations based on roughness models of various degrees of complication. These relations are established on the basis of the results of some tests of the surfaces of elements machined by the same methods and made of the same materials as the elements to be analysed. These methods enable us to evaluate contact deformations with an accuracy which is much better than that of the theoretical methods. Another method for ensuring the required rigidity of manufactured objects is by direct measurement of contact deformation in the course of the manufacturing process, for which a special apparatus is required. The devices which have been designed for the measurement of contact deformations of a surface enable such measurement by using a check surface of high hardness and low roughness as compared with those of the parts considered.     

Multi-grooved cutting tool to reduce cutting force and temperature during bone machining

The cutting temperature of a cutting tool are required to be low during bone machining for preventing damage to bone cells. However, conventional tools are practically the same as those used for metal cutting, and many operational limitations have been reported. In this study, a dedicated cutting tool was designed for reducing cutting force and temperature. A short contact between the workpiece and the cutting edge leads to a reduction in the cutting force. Furthermore, a straight-line edge improves surface roughness. The effectiveness was evaluated using bovine bone, and the cutting force was found to be decreased by about 40%.     

Innovative use of biologically produced ferric sulfate for machining of copper metal and study of specific metal removal rate and surface roughness during the process

The biologically produced ferric sulfate (in the form of bacterial culture supernatant) was used for machining of copper metal workpiece. A 27.04 mg/h cm² average specific metal removal rate was achieved during oxidation of copper workpiece. The leaching performance of culture supernatant was comparable to that of microbial cells indicating that an indirect non-contact leaching mechanism is predominant for metal solubilization. The surface of copper workpiece was analyzed by scanning electron microscopy before and after oxidation. The changes in surface appearance were found during oxidation of copper. Also the change in surface roughness was observed during machining process. The quality of the surface produced is a very important aspect of the performance of the manufacturing process. Therefore the present study characterizes an effect of various physicochemical parameters on specific metal removal rate and surface roughness. An increasing concentration of FeSO₄, shaking speed and volume of culture supernatant showed pronounced effect on metal removal and surface roughness. At the same time an application of varying temperatures showed little effect.     

Cutting process of glass with inclined ball end mill

Cutting processes with ball end mills are discussed for machining microgrooves on glasses. A surface is finished in undeformed chip thickness less than 1 μm at the beginning and at the end of the cut during the cutter rotation. The milling process is applied to glass machining. A crack-free surface can be finished in a large axial depth of cut more than 10 μm. Because glass undergoes almost no elastic deformation, roughness on a cutting edge in glass machining has a larger influence on surface finish than that of metal machining. The rotational axis of the tool is inclined to improve the surface finish. The cutting processes are modeled to show the effect of the tool inclination on the machined surface with considering the edge roughness. The tool inclination compensates for deterioration of the surface finish induced by the edge roughness in the presented model. The improvement of the surface finish is verified in the cutting experiments with the tool inclination. The orthogonal grooves 15–20 μm deep and 150–175 μm wide, then, are machined with the crack-free surfaces to prove efficiency and surface quality in the milling process.     

磁流变抛光非球柱面镜的新工艺

高精密的柱面镜光学元件,不但要求其具有极低的表面粗糙度、无表面/亚表面损伤和低的残余应力等,而且需要保证其柱面母线的平行度与垂直度。通过分析传统磨研抛技术和计算机控制的光学表面成型技术(CCOS) 2种技术对柱面镜加工后的表面粗糙度、面形精度和母线误差的影响,归纳2种加工方法的优缺点,针对现有加工方法存在的低效率、高粗糙度、表面/亚表面损伤等问题提出一种具有对称结构的非球柱面镜磁流变抛光新工艺,并通过时间参数实验验证了新工艺的可行性。该工艺降低了柱面镜的表面粗糙度,提高了面型精度,在抛光时间为40 min时,表面粗糙度R_a从1.84 μm降低至0.36 μm,局部面型精度RMS₁从 1.91 μm降低到0.24 μm,母线截面面型精度RMS₂从4.1 μm下降到0.68 μm。      

N6镍铣削表面粗糙度与铣削力-铣削振动的耦合特性研究

为了研究铣削工件表面质量与铣削力-铣削振动的耦合关联特性,搭建铣削力-铣削振动-表面粗糙度测试系统,设计铣削三参数全因子试验方案,对N6镍金属进行铣削试验,同步采集三向铣削振动和铣削力信号,利用粗糙度测量仪测量工件表面粗糙度。基于灰色关联分析法,计算工件表面粗糙度与铣削力、铣削振动及铣削参数等多因素的灰色关联度,得到了影响表面粗糙度最显著的因子。基于响应面法,建立铣削工件表面粗糙度关于铣削振动-铣削力的耦合模型。对相关系数值、粗糙度拟合值与实测值的对比曲线及残差散点图等的研究表明：镍金属表面质量与切削振动-铣削力的耦合效应显著,耦合模型拟合数据的优度很高,可以较好预测N6镍金属的表面粗糙度。     

放电诱导可控烧蚀高效加工典型工艺方法

提出了一种以放电诱导产生可控烧蚀为基础的高效加工方式。利用大部分金属在放电诱导后表面产生活化区会与通入的氧气发生燃烧的特点,通过放电诱导,使加工表面产生活化区,并控制氧气的通入量,使加工表面金属产生可控高效烧蚀,而后通过电火花加工、电解加工、车削、铣削、磨削等工艺方法修整烧蚀表面,完善表面质量与精度。此种加工方法特别适合于钛合金、高温合金、高强度钢等难加工金属材料的加工。由于采用水溶性非可燃工作液,节能环保,不会产生有害气体及燃烧隐患,因此也是一项绿色制造技术,是机械加工领域一种全新的高效加工方法。     

Surface characterization in ultra-precision machining of Al/SiC metal matrix composites using data dependent systems analysis

This paper presents a data dependent systems (DDSs) method for the analysis of surface generation in ultra-precision machining of Al/SiC metal matrix composites (MMCs). The DDS analysis provides a component by component wavelength decomposition of the surface roughness profile of the machined surface. A series of face cutting experiments was done on Al6061/15SiC_p MMCs under different cutting conditions. The cutting results indicate that the characteristics of the wavelength components analyzed by the DDS analysis method are correlated well with the surface generation mechanisms. Since the relative powers of the wavelength components are used to measure the contributions of the cutting mechanisms to the total roughness, this resolves the shortcomings of the conventional spectrum analysis method in characterizing the surface properties such as pits and cracks in ultra-precision machining of MMCs.