金刚石刀具刀尖圆弧波纹度的测量及评价

为实现金刚石刀具刀尖圆弧波纹度超精密测量,构建了基于原子力显微镜(AFM)和精密回转轴系的刀尖圆弧轮廓测量系统,研究了刀尖圆弧波纹度评价方法和控制测量系统引入误差的策略。提出了评价刀尖圆弧波纹度时截止波长的确定原则和方法,并介绍了刀尖圆弧波纹度测量原理及评价流程。讨论了精密回转轴系径向回转误差的测量和评定、刀具安装偏心和偏角误差的控制和原子力扫描系统Z向非线性误差的校准方法。最后,在构建的测量系统上测量了了金刚石刀具刀尖圆弧波纹度并对测量不确定度进行了分析。实验测量显示:所评价金刚石刀具的刀尖圆弧波纹度为0.106μm,测量不确定度为23.8nm,表明所构建的测量系统基本满足金刚石刀具刀尖圆弧波纹度纳米级测量及评价的需求,测量结果稳定可靠、精度高。     

Automatic identification of feed marks in machined surface roughness profiles by correlating random variations

A new method is detailed to identify the positions of the ends of the tool marks in linear surface roughness profiles. No feed mark shape must be assumed and the process is entirely automated. The approach may find applications in automated quality control, surface texture classification, and modeling of metal cutting processes. Validation was done with 40 finish hard turning specimens. The method relies on the justified hypotheses that a feed mark profile is a superposition of a fixed and a random component, and that the random component has a spatial period equal to one feed mark length. A brief typology of tool mark particularities revealed by the method is presented as well as observations on the correlation of the random events within marks and between marks, both at short and at long range. Feed marks difficult to identify by visual inspection were easily identified with the method and evidence of overlapping tool marks and unstable regions was discovered. The limits of the method are also explored.     

Wear behavior of chromium nitride coating in dry condition at lower sliding velocity and load

Quantitative information about the contributions of individual cutting phenomena to linear roughness profiles may aid in optimizing processes with fewer expensive successive trial parts. Linear roughness profiles of metallic hard turned parts contain feed marks, each mark representing a snapshot in time of the state of the cut. This suggests that roughness measuring machines may be an attractive avenue for offline, inexpensive, non-destructive, quantitative evaluation of the time-dependent mechanisms active during the cut. Principal component analysis of feed marks reveals theoretically expected feed mark deformations without coercing the data by fitting. Novel in this paper, we show that those components of feed mark variability appear to correspond to radial and axial displacement of the cutting tool, ploughing, and side flow. Those components are sufficient to explain nearly all the variability between feed marks. The components are easily idealized in a general manner, and their influences on experimental profiles are quantified as percentage contributions to ordinary roughness parameters.     

A Study on the Influence of Waviness Error to a Hydrostatic Bearing for a Crankshaft Pin Turner

This article describes a theoretical analysis of a hydrostatic journal bearing for a crankshaft pin turner by considering the waviness error of the journal and bearing. The authors found adequate design parameters to operate the crankshaft pin turner bearing. The flow rate, radial clearance, and eccentricity were selected as the basic design parameters. The load-carrying capacity of the bearing as a function of the design parameters was studied in the case of a true circular journal and bearing. The influence of the waviness error on the load-carrying capacity was then investigated; cosine functions were selected for the waviness functions. As a result, the load-carrying capacity varied according to the amplitude and phase angle of the waviness functions. Thus, it was found that the influence of the waviness error is a significant factor in analyzing lubrication characteristics.

Run-out accuracy analysis method according to the waviness phase angles of the journal and bearing was suggested. It was found that the phase angles between the bearing load wave and load-carrying capacity wave are important factors that affect the running accuracy in addition to the amplitude of waviness error.     

Automated bullet-identification system based on surface topography techniques

Every firearm has individual characteristics that are as unique to it as fingerprints are to human beings. When a firearm is fired, it transfers these characteristics – in the form of microscopic scratches and dents – to the fired bullets and cartridge casings. The rifling of the barrel of the firearm marks the bullets travelling through it, and the firearm's breech mechanism marks the ammunition's cartridge casing. Characterising these marks is the critical element in identifying firearms.Traditionally the comparison of ballistic evidence has been a tedious and time-consuming process requiring highly skilled examiners. In the past decade, engineers have created automated ballistics identification systems that meld traditional comparison microscopes with digital cameras, computers, huge databases, and image analysis techniques. This kind of system can help investigators to link crimes by automatically finding similarities among images of bullet but suffering significant drawbacks and minimal matching.More recently, approaches based on 3D digital representations of evidence surface topography have started to appear, both in research and industrial products. Potentially the introduction of 3D surface topography measurement can overcome the limitations of digital imaging systems by making the bullet surface measurement reproducible and reliable. A 3D quantitative approach for bullet identification is proposed in this paper. In this system the surface topography of the whole bullet can be acquired for analysis and identification. Primary researches have been done by applying advanced surface topography techniques for bullet marks’ characteristics extraction. A variety of 2D and 3D visualization graphics have also been provided to help firearm examiners to make final decisions.     

Multi scale modal decomposition of primary form, waviness and roughness of surfaces

This article introduces an innovative method for the multi-scale analysis of high value-added surfaces, which consists of applying a method based on a new parameterization. This kind of surface parameterization refers to natural modes of vibration, and is therefore named modal parameterization. It allows us to characterize the form, waviness and roughness defects of a surface. This parameterization opens up new fields of analysis, such as the appearance quality of surfaces. It is thereby possible to decompose a measured surface in a vector basis, of which vectors are represented by plane natural eigenmodes sorted by frequency and complexity. Different filtering operations can then be produced, such as extracting the primary form of the surface. To analyze the perceived quality of surfaces, these investigations focus on two approaches: that appearance defects have small periodicity, and that there is a link between curvatures and the visual impact of an anomaly. This methodology is applied to two prestige lighters, whose surfaces were measured by extended field confocal microscopy. Moreover, a prospect of this work is to develop an augmented-reality-type monitoring tool for sensory experts.     

Improving waviness of bore in precision hard turning by pressurized coolant

Precision hard turning is an emerging innovated machining technology for machining hardened workpiece (60~62 HRC) with characteristic of better flexibility, high production rate, and cost saving. However, one of problem in this process is that it is difficult to remove the thermal distortion of the workpiece induced by the heat generated during the process, especially in the case of precision hard turning of bore. In this paper, pressurized coolant was used in a precision hard turning of bore, with polycrystalline cubic boron nitride as the tool materials, to reduce the thermal distortion of the machined part such as form error and to improve its waviness. The pressurized coolant jet was directly delivered under the chip on the rake face. Experimental result indicated that form error induced by the heat has been reduced, and waviness of the bore was improved with use of pressurized coolant. Crater wear is smaller under pressurized coolant compared to dry cut due to lower rake face temperature and shorter contact length between chip and workpiece.     

基于并行共聚焦显微系统的物方差动轴向测量

差动共聚焦显微成像技术可以获得很高的轴向测量精度,然而已有的差动共聚焦测量技术主要适用于激光扫描共聚焦,还不能满足微纳加工过程中对工件进行非接触式的在线、在位测量的要求。本文在分析差动共聚焦显微成像系统能够实现轴向测量原理的基础上,提出了适用于并行共聚焦技术的轴向测量方法。该方法利用均匀白光照明,在像方只需要使用一台相机做探测器,在物方通过移动载物台分别对样品在焦前和焦后两次成像,根据预先刻度好的差动曲线就可以得出物体表面的高度。理论模拟与实验结果均表明,该方法可以实现高精度的轴向测量,对500nm的台阶样品测量的平均误差为2.9nm,相对误差为0.58%。该方法简单、廉价、测量精度高,可以用于普通显微镜,易于实现样品的三维快速形貌还原与测量。     

对金刚石刀具刀尖圆弧波纹度评价的滤波分析

为准确评价超精密金刚石刀具刀尖圆弧波纹度,对金刚石刀具刀尖圆弧波纹度的评价进行了滤波分析。介绍了刀尖圆弧波纹度的评价方法,针对关键的滤波环节,分析了高斯滤波、高斯回归滤波、样条滤波和小波滤波的原理,根据实际采样数据设计模拟实验对比了上述4种滤波器的滤波特性。结果表明,对于不同轮廓中线但高频分量完全相同的轮廓,样条滤波器的滤波效果优于高斯滤波器,并通过实际应用对比了高斯滤波器和样条滤波器。实验结果表明:对具有不同轮廓中线但高频分量完全相同的模拟轮廓,分别采用高斯滤波器和样条滤波器,当截止波长分别取0.25mm和0.8mm时,高斯滤波器滤波结果的标准差分别为0.4366nm和9.6544nm,样条滤波器滤波结果的标准差分别为0.0271nm和1.1844nm,说明样条滤波器更适合于超精密金刚石刀具刀尖圆弧波纹度的评价。     

数控车床加工特殊螺纹接头产生颤纹的原因及对策

颤纹是特殊螺纹接头生产加工过程中普遍存在的现象,不仅影响特殊螺纹接头的表面质量,而且会导致特殊螺纹接头的各项性能恶化。本文从车床、刀具的刚性,试样的装夹情况,刀具的设计安装,加工工艺参数及加工方式的选择等几个方面对特殊螺纹接头加工过程中颤纹的产生原因进行了深入分析,并提出了相应的对策,为特殊螺纹接头的生产质量控制提供了一定参考。     

凸圆弧前刀面铣刀头超精铣削时主要参数对粗糙度及残留面积的影响

通过详细推算,给出凸圆弧前刀面金刚石铣刀头超精铣削平面时的理论表面粗糙度和切削残留面积的计算公式.利用所得的公式,进一步分析了凸圆弧半径、走刀、后角及安装误差角等主要参数对它们的影响.其Ra值可达几个纳米、P-V值达亚微米级.     

Validation of two dual fluorescence techniques for confocal microscopic visualization of resin penetration into enamel caries lesions

Fluorescence confocal microscopy is a useful tool to analyze the infiltration of enamel caries lesions with low-viscosity resins (infiltrants) in vitro. The conventionally used staining technique, which comprises dye labeling of the resin, has been shown to be limited by chromatographic separation of the resin-dye-mixture during penetration. The aim of this study was to develop an improved dual staining technique and to compare validity and reproducibility of both methods. Human molars with proximal white spots were cut across the demineralizations. After varnishing the cut surfaces, paired lesion halves were infiltrated with an infiltrant using either one of two different staining techniques. For the conventional direct technique (A) the infiltrant was labeled with rhodamine isothiocyanate (RITC) prior to application. Using the new indirect technique (B) lesions were stained with RITC solution and subsequently infiltrated with pure infiltrant. After light curing, unbound dye was bleached by immersion in hydrogen peroxide. Remaining lesion pores were stained with sodium fluorescein solution. Penetration depths (PD) and lesion depths (LD) were evaluated by five examiners using confocal microscopy and compared with the results of scanning electron microscopic (SEM; PD) and microradiographic (TMR; LD) analysis. The indirect technique showed better correlation (intraclass coefficients) with SEM (0.990) and TMR (0.982) compared with the direct technique (SEM: 0.513; TMR: 0.702). Inter- and intrarater reliability was higher for technique B compared with technique A. The new indirect technique yields to more valid and reliable results to visualize infiltrant penetration into natural enamel caries lesions compared with the conventional method. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc.     

Investigation of the burnishing process with PCD tool on non-ferrous metals

It is well known that the no-chip machining process, burnishing, can easily improve surface roughness, waviness and hardness. To get the practical useful parameters, the effects of various burnishing parameters (spindle speed, depth, feed, burnishing radius and lathe) on surface roughness and waviness of the non-ferrous components were studied experimentally with a theoretical analysis. The experiments were conducted with a simply designed cylindrical surfaced polycrystalline diamond tool developed by us. It was found that smaller parameters do not mean lower surface roughness or waviness and different optimum burnishing parameters can be got under different burnishing conditions.     

补偿运动误差新的诊断原理及系统

本文就补偿运动误差提出了新的诊断方法及系统。新方法将运动误差变换到被切轮齿法向进行考虑。新系统不需像传统方法一般采用精密元件组成基准系统而是可用被测机床精切后的工件测量元件,运用误差相关和误差分离原理,求解补偿运动误差和工件齿面波度误差,并捕捉二者误差的主源。文章给出了实例。     

辊筒模具微透镜阵列的慢刀伺服成形加工

目的：为实现辊筒模具表面微透镜阵列高效率、高精度加工,本文对微透镜阵列成形法加工轨迹的拟合方法和机床伺服参数的优化方法进行了理论与实验研究。首先,分析了微透镜阵列的原始轨迹特征,确定了过渡台阶的突变是微透镜表面振纹的主要诱因。其次,为保证加工轨迹二阶导数的连续性,本文提出了三次样条插值与傅里叶级数拟合拼接的方法优化加工轨迹。最后,在优化加工轨迹的基础上,通过调整伺服系统的前馈参数,提高了进给轴响应能力,减小了因驱动质量和阻尼效应而产生的跟踪误差。口径800μm、深度26.7μm的微透镜阵列加工实验表明,采用优化的刀具轨迹和伺服参数,机床加工效率可以达到8Hz,进给轴跟踪误差小于300nm,消除了微透镜阵列的表面振纹。微透镜单元口径的尺寸误差约为设计值的1.075%,随机检测结果表明口径尺寸变化范围为2μm,加工一致性良好。三次样条插值与傅里叶级数拟合优化的加工轨迹可有效抑制进给轴的振动,改善了微透镜阵列表面质量。     

Minimization of sink mark depth in injection-molded thermoplastic through design of experiments and genetic algorithm

This paper deals with minimization of sink marks occurring behind the rib in plastic injection molding. In terms of rib structure and injection processing parameters, a theoretical analysis model was created. Meanwhile, finite element flow analysis with design of experiments (DOE) and genetic algorithm (GA) was integrated. Values of sink mark depth depend on design variables and technological parameters. Out of all, the four most influential variables, viz., rib thickness, mold temperature, melt temperature, and coolant temperature, were selected for optimization. The mathematic relation between sink mark depth and variables was established by conducting a set of FE analyses at various combinations of variables based on central composite design (CCD). Furthermore, the influence incidence of each factor and interaction between each variable on sink marks were investigated. The prediction model of sink marks was effectively coupled with GA for optimization of variables to minimize the sink depth. Results of the contrast analysis indicated that the proposed methodology could be used effectively in minimizing sink mark depth and parameter optimization design.     

Virtual biopsy of the joint tissues using near-infrared, reflectance confocal microscopy. A pilot study

Standard noninvasive imaging techniques applied to joints provide gross morphological features, insufficient for assessing histological detail. On the other hand, biopsying is invasive, time consuming, and may involve unwanted processing artifacts. Near-infrared reflectance confocal microscopy is a technique that allows serial, high-resolution optical sectioning through intact tissues without employing exogenous fluorescent stains. The aim of this work was to evaluate the potential utility of near-infrared reflectance confocal microscopy for providing immediate histological information on meniscus, articular cartilage, epiphyseal plate, bone, muscle, and tendon. Images from near-infrared reflectance confocal microscopy were compared with mirror routine histology sections. Characteristic architectural features were readily visualized in the three dimensions of space. Additionally, the use of experimental contrast agents highlighted the localization of nuclei. Limitations include penetration depth and minor optical artifacts. In conclusion, near-infrared reflectance confocal microscopy is a useful technique for immediate, nondestructive, serial "virtual" sectioning through intact tissues, being thus a potential adjunct to current imaging techniques in orthopedics.     

Study on the response surface model of machining error in internal lathe boring

To achieve high quality and precision of machining products, the machining error must be examined. The machining error, defined as the difference between designed surface and the actual tool, is generally caused by tool deflection and wear, thermal effects and machine tool errors. Among these error sources, tool deflection is usually known as the most significant factor. The tool deflection problem is analyzed using the instantaneous cutting forces on the cutting edge. This study presents a model of the machining error caused by tool deflection in the internal boring process. The machining error prediction model was described by the surface response method using overhang, feed per revolution and depth of cut as the factors for the analysis. The least square method revealed that overhang and depth of cut were significant factors within 90% confidence intervals. Analysis of variance (ANOVA) and residual analysis show that the second-order model is adequate.     

出刃高度差对金刚石有序排布工具的影响

采用单颗粒金刚石沿不同的切削路径(不同间距切痕或重叠切痕)与不同切削深度的组合形式进行了平面划擦广西白大理石的试验。分析了两种切削路径下出刃高度差对有序排布金刚石工具切削力Fz的影响,结果表明:在不同间距切痕的条件下,当ap1<20μm、L2<200μm时,第二道切痕切削力随着出刃高度差的增大而急剧增大,而当L2>600μm时,出刃高度差的增大却对第二道切痕切削力的影响较小,而当ap1>30μm时,可切削性能随着出刃高度差的增大而变差,但切痕距离越小越有利于切削加工,但影响较小;在重叠切痕条件下,当出刃高度差apx<30μm时,第二道切痕的切削力随着出刃高度差的增大而增大,而当出刃高度差apx>30μm时,却恰恰相反;在两种切削路径下,随着第一道切痕的切削深度ap1的增加,切痕重叠的可加工性能要更优于切痕间距。     

Airbag tool polishing for aspherical glass lens molds

This paper presents a novel airbag tool polishing technique for small aspherical glass lens molds. For a mold material such as tungstencarbide, an ultra-precise grinding technique is used to generate the aspherical surface. However, the residual tool marks of the spiral pattern and scratch unavoidably develop on the mold surface. Therefore, post-polishing is required to obtain the optical surface. Footprinting by the superposition method without trajectory control was applied to polish the finely ground aspherical lens mold. A white light interferometer confirmed the tool mark removal effect. The final surface roughness was Ra 2nm. Microscopic observation also showed a cleaner surface without scratches.