汽车用薄板的表面形貌的分形研究

本文将分形理论用于薄板表面形貌的研究上,提出了分形维数反映了表面形貌的规律性的观点。利用触针轮廓仪和数据采集系统对几种不同的毛化薄板的三维形貌进行了测量,计算了这些薄板的分形维数,并对这些薄板的表面形貌的规律性进行了讨论。     

基于冗余提升形态小波的非对称表面特征提取研究

针对提升小波提取非对称表面形貌特征时存在平移变动性和较差的方向选择性,将具有平移不变性和良好的方向选择性的冗余提升形态Haar小波应用到非对称表面的特征提取中。开展了该形态小波对具有显著特征的非对称平顶珩磨的缸套内表面进行特征提取的分析;同时结合仿真的方法,研究了该形态Haar小波对一个模拟的具有一定长度沟槽特征的空间表面进行特征提取的效果。研究结果表明,冗余提升形态Haar小波对非对称表面形貌进行形态特征提取时,在各尺度重构的信号沿特征边缘几乎没有变动且无畸变,可实现准确提取。     

变截面涡旋齿三维形貌分析与功率谱密度表征

为了量化表征变截面涡旋齿形貌的变化规律并提取特征信息,以45#钢和硬铝7075材料进行了3段基圆渐开线变截面涡旋铣削加工实验,用Talysurf CLI 1000形貌仪测量了涡旋齿三维形貌和表面粗糙度,对形貌图像进行了分析和比较,运用一维和二维功率谱密度方法量化表征了涡旋齿形貌的频率?空间分布信息。形貌分析表明：45#钢试样涡旋齿形貌变化趋势接近走刀痕迹,呈现较强的规律性;45#钢涡旋齿试样表面形貌变化高度大于硬铝7075,且形貌的变化与型线位置无明显联系。二维功率谱密度分析表明,涡旋齿形貌呈各向异性特征,x方向空间频率0~0.02 μm-1是影响涡旋齿形貌的主导频率,涡旋齿主要缺陷存在于空间波长50 μm内。一维功率谱密度表征解析了涡旋齿试样粗糙度相近、但表面形貌和粗糙度差异性明显的现象。实现了涡旋齿形貌不同层次特征的定量表征和信息提取。     

覆盖件模具拼接区表面微观几何形貌的反演分析

为提高车身覆盖件模具拼接区的加工质量,首先分析不同加工参数下拼接缝前后的表面形貌几何特性和残留高度的空间特性,然后基于小波包提取加工表面轮廓信号不同频段的能量熵特征,最后根据能量熵特征、材料去除率和刀具寿命预测函数反演表面形貌的加工参数。研究结果表明,基于反演分析方法得到的加工参数可以实现拼接区微观几何形貌的可控。     

基于小波变换和分形维数的表面微观形貌分析

针对传统三维参数和单一分形维数在表面微观形貌分析中的不足,提出了一种基于小波变换和分形维数的表面微观形貌分析方法。该方法通过小波变换对表面形貌的灰度图像进行分解和单支重构,利用改进的差分盒维法计算原图像和重构子图像的分形维数,依据原图像和重构子图像的分形维数构成的数组对表面微观形貌进行分析。最后,利用本文提出的方法对一组零件的表面微观形貌进行了分析,结果表明原图像和重构子图像的分形维数不仅能够反映表面微观形貌的整体特征还能反映表面不同分辨率下的细节特征。     

表面测量与分析在调控加工中的应用

对超精车削加工中得到的表面进行表面仿真分析.通过分析其表面空间频谱,确定表面微观形貌特征与加工参数、切削振动之间的关系,为调控加工过程提供理论依据.     

轧制速度对高纯铝箔表面形貌的影响

以不同的速度对高纯铝箔进行轧制试验,用非接触式三维表面轮廓仪观测了铝箔表面形貌,并从润滑状态、表面轮廓自协方差函数及功率谱密度等方面研究了轧制速度对铝箔表面形貌的影响。结果表明:在轧制过程中,摩擦主要是由轧辊表面微凸体压入高纯铝表面产生的塑性变形及犁沟作用所致;铝箔的表面粗糙度主要取决于轧辊的表面粗糙度,轧制速度的变化不会影响铝箔表面轮廓的主要特征;轧制速度从5m.s-1提高到7m.s-1后,铝箔横向表面粗糙度无明显变化,而轧向表面粗糙度下降,表面微观形貌得到了改善;轧制速度的变化不影响铝箔表面轮廓的自相关性,铝箔的表面轮廓以空间波长较长的空间随机分量为主。     

冷轧板表面起皮缺陷研究

为了提高冷轧薄板的成材率,研究了冷轧薄板表面条痕缺陷的宏观和微观特征,提出夹杂物、铸坯表面裂纹、气泡是形成表面缺陷的主要原因.严格工艺操作可减少或消除缺陷.     

单晶硅磨削表面脆塑转变表征方法

为了对单晶硅磨削表面脆塑转变特征进行有效的表征,研究了单晶硅脆塑性磨削模式下的表面形貌。首先,基于工件旋转法磨削原理,对单晶硅进行了磨削试验。然后,利用三维形貌轮廓仪和扫描电子显微镜对不同磨削速度下的单晶硅表面形貌进行了测量和分析。最后,利用表面脆性破碎面积百分比Sbf、表面破碎率Sc、分形维数DL、表面纹理纵横比Str等参数对单晶硅磨削表面脆塑转变特征进行了研究。通过不同表征方法的对比分析,得出了基于参数Str的单晶硅磨削表面脆塑转变特征的有效表征方法。     

超精加工表面形貌任意频率的提取及重构

采用功率谱密度(PSD)和连续小波方法(CWT)相结合的方法分析磷酸二氢钾(KDP)晶体超精加工表面形貌中的频率特征。采用PSD提取取样长度和周期范围内表面形貌上的所有频率特征,针对PSD得到的三个显著实际频率特征进行频率的提取,同时获得CWT的尺度因子a;用Mexican Hat小波函数实现连续小波变换还原实际频率形貌。结果表明:在采样域内,实际频率为0.0138μm~(-1)的表面形貌与原始表面极为接近,是KDP晶体超精加工表面形貌及影响表面粗造度的主要频率特征。     

An analysis of the three-dimensional surface topography of textured cold-rolled steel sheets

The surface topography of cold-rolled steel sheet affects its press-forming behaviour and also influences the appearance of the end product after painting. In this study, the three-dimensional surface topography of several steel sheets processed by different technologies has been measured. Using statistical and signal processing techniques, two-dimensional power spectral density function, two-dimensional autocorrelation function and two three-dimensional characteristic parameters of the surface topography of each steel sheet are obtained separately. Through analyzing these parameters and charts of the functions, an investigation on three-dimensional surface topography of these steel sheets is performed.     

毛化钢板表面形貌表征方法的研究

目前钢板表面形貌的表征参数和方法还存在不足,本文针对钢板表面的摩擦学功能特征,提出了二维轮廓和三维表面的特征参数,并给出了计算方法。通过正弦、三角和克吕斯3种典型凸峰模型和表面模型,以及不同毛化钢板表面形貌的对比研究,说明特征参数能准确反映钢板的承载性能和储油性能。     

On the influence of imaging conditions and algorithms on the quantification of surface topography

The influence of the microscopical magnification resulting in different voxel size and shape and of the algorithm on parameters used for the quantification of the surface topography is studied using topographical images obtained by confocal laser scanning microscopy. Fracture surfaces and wire‐eroded surfaces of steel were used as samples. The values obtained for the global topometry parameters normalized surface area, mean profile segment length and fractal dimension depend with different degrees on the microscopic magnification and on the algorithm used to compute these values. The topometry values can only be used to establish correlations between the topography and materials properties and for the modelling of surface generating processes if the imaging and computing details are given.     

Experimental Study on the Friction Characteristics of Lasertex Steel Sheets During Metal Forming Process

The surface of steel sheets used in the metal-forming process discussed in this article was textured by a laser-ablation technique. Differently shaped craters are formed in a patterned structure on the steel surface by controlling the pulsed-laser power density, pulse-repetition rate, and pulse duration. Lasertex sheets formed by this process have unique friction characteristics because of the uniform surface roughness and valley-biased topography. The friction of lasertex sheets was studied using a metal-forming bench test rig. Influencing factors, including surface roughness and sliding velocity, were studied under lubricated conditions. The friction of lasertex sheets was compared with that of shot-blasted sheets. The results showed that the coefficient of friction of the lasertex sheet under dry friction decreases with an increase in surface roughness and changes little with varying sliding velocity. With lubrication, the coefficient of friction of the lasertex sheet rises with an increase in surface roughness and decreases with an increase in sliding velocity. Lasertex sheets were found to have lower friction coefficients than shot-blasted sheets over the rage of surface roughness and sliding velocity investigated.     

The characteristics of cutting forces in the micro-milling of AISI D2 steel

The interaction effect of parameters to surface topography and cutting forces is investigated, and the magnitudes of these parameters are determined in the micro-milling of AISI D2 steel. The results show that the feed per tooth has a prominent impact on the surface topography. Due to the low feed per tooth to cutting edge radius ratio, a high surface roughness and a high amount of burrs are obtained in micro-milling. In micro cutting, the cutting forces present are small; in addition, the radial thrust cutting forces are greater than the principal cutting forces. This research proves that the micro-milling process can be applied to the manufacturing of AISI D2 steel micro parts and presents experimental evidence and possible solutions to the cutting parameters.     

Experimental methodology to study tribological aspects of deep drawing — application to aluminium alloy sheets and tool coatings

To optimise the contact between aluminium alloy sheets and coated HSS steel tools during deep drawing operation, we present an experimental methodology to decompose an extended slippage by using a strip drawing test with cylindrical tools in multipassing mode. We show in this paper the role of transfer films formed on the tool surface on the evolution of both friction coefficient and surface topography of the metal sheet.     

Developing Techniques for Testing Magnetic Properties of Electric Steels. II. Variations in Magnetic Properties and Their Effect on Reliability of Testing Results (review article)

The paper presents experimental data concerning the magnitude and character of variations in magnetic properties of electric steels (among a number of sheets, within one sheet, over the length and width of a roll, etc.). The paper also considers effects of variations in magnetic parameters of steel on the quality of fabricated components and reliability of measurements of steel parameters conducted in accordance with the existing State Standards by testing one selected sample cut from single sheets of a batch, or from the beginning or end of a roll on an Epstein's apparatus. The inhomogeneity of magnetic parameters is a natural consequence of the instability of the technological process of the steel manufacture on all its stages and on the stages of its transformation (chemical composition, smelting conditions in which slabs for rolling are produced, regimes of rolling and annealing, etc.), therefore these parameters usually obey the law of normal distribution. Feasibility of more efficient methods of steel testing designed to optimize and improve the reliability of testing results is discussed.     

压电力传感器晶片与电极接触刚度影响研究*

以压电力传感器为核心的多分量测量系统是航空、航天等领域重要的力学测量装置。压电力传感器中晶片与电极结合面接触刚度是基础性能参数,对压电力传感器的分载效应及灵敏度,多分量测量系统的整体刚度及静、动态性能有直接影响。由于尚无对该参数的研究,导致在设计封装压电力传感器过程中缺少相应的理论依据,在使用多分量测量系统时存在标定困难等问题。针对以上问题,研究晶片与电极结合面接触刚度的影响因素,建立基于分形理论的接触刚度模型,优化了晶面表面形貌、压电材料、电极材料、预紧力等参数。在此基础上,研究接触刚度对传感器性能——刚度、灵敏度、固有频率等影响,提出一种以接触刚度为约束的晶片表面形貌优化方法。基于结构函数法,建立分形理论与实际工程测量参数的联系,通过两种压电晶体——石英与硅酸镓镧,四种电极材料——钛合金、不锈钢、黄铜、铝,试验验证了理论模型。试验表明,优化晶片表面分形参数、提高预紧力、选用弹性模量小的电极有助于提高晶片与电极接触刚度,进而提高传感器的整体刚度、灵敏度和固有频率。研究为高性能压电力传感器的设计提供了理论参考。     

The influence of topography on the specific dissipated friction power in ultra-mild sliding wear: Experiment and simulation

Current political, economic and ecological guidelines demand the increase of power densities of nearly all machinery parts. In order to further lower the wear rate towards the ultra-mild sliding wear regime, an integral approach is needed, which has to regard contact conditions, surface topography, surface chemistry, as well as sub-surface properties. Still, there are no simple parameters to classify the performance of a tribosystem. In this study the area affected by tribocontacts is calculated by means of a three dimensional elastic–ideal plastic contact model. The surfaces are prepared by means of conventional machining procedures and characterized by scanning white light interferometry. The further input data as to normal and friction forces are derived by reciprocating sliding wear tests under boundary lubrication conditions of carburized steel against carburized steel and 52100 steel against case-hardened spheroidal cast iron. This contribution will depict the distinct influence of the topography on friction and ultra-mild sliding wear of common Fe-base materials and point out the marked importance of highly localized effects, which govern the acting mechanisms.