铁氧体陶瓷材料的磨削表面粗糙度试验研究

结合单因素和正交试验全面分析了不同磨削工艺参数及砂轮特性对铁氧体陶瓷的磨削表面粗糙度影响规律,为铁氧体零件的磨削加工提供了依据.     

铁氧体陶瓷高效磨削技术研究

通过试验研究了不同磨削参数对铁氧体的表面粗糙度、磨削力、磨削效率的影响规律,并在此基础上探讨了铁氧体的高效磨削技术。     

基于主成分分析的高速铣削振动特性研究

为获得更加精确的高速铣削钛合金表面粗糙度预测模型,采集铣削过程加速度振动信号,分析铣削系统的振动特性对表面粗糙度的影响。通过功率谱分析量化振动信号特征,并用主成分分析简化数据结构,得到的振动特征量能反映原始数据89.719%的信息。最后以振动特征量和铣削参数为影响因素,建立了表面粗糙度的预测模型。结果表明,主轴的振动特性对表面粗糙度的影响大于工作台,刀具进给方向的振动特性对表面粗糙度的影响大于其余方向。     

树脂结合剂金刚石砂轮磨削铁氧体陶瓷表面粗糙度的试验研究

通过磨削对比试验研究了树脂结合剂金刚石砂轮的特性参数和磨削用量对铁氧体陶瓷表面粗糙度的影响;通过砂轮速度、磨削深度、横向进给速度和纵向进给速度等四因素及各因素之间交互试验的数据分析和金相显微图像比较,探讨了各因素对陶瓷表面粗糙度的影响规律,并优化了降低表面粗糙度的磨削参数。     

基于表面粗糙度预测的数控车削加工物理仿真模型的研究

通过分析数控加工中表面粗糙度的产生原因,提出了表面粗糙度仿真系统模型的结构,建立了切削力、振动和表面粗糙度的数学模型,为通过物理仿真预测加工表面粗糙度提供了理论依据。     

TA15钛合金切削振动与表面质量关系研究

通过单因素试验对TA15进行外圆车削加工,采集振动信号并提取信号特征值,分析了切削用量对切削振动和表面粗糙度的影响规律,揭示切削用量对振动的影响,并根据正交试验结果分析切削用量对振动和表面粗糙度影响的主次关系,得到优化的切削用量。试验研究表明:切削用量中,切深对切削振动影响最大,其次为进给量,切削速度影响最小。改变进给量时,振动加速度与表面粗糙度近似成线性正比关系;改变切深时,振动加速度随表面粗糙度的增加而增加。     

表面粗糙度对轴承振动的影响

利用Fokker-P lanck方程分析表面粗糙度对滚动轴承振动的影响,结果表明,在表面凸峰处接触振动很小,而在表面凹陷处接触振动的振动速度、加速度很大。表面粗糙度对高速轴承的振动影响较低速轴承要大;表面粗糙度Ry对接触振动影响不大;接触载荷对接触振动影响很显著,接触载荷越大,在凹陷处的接触振动加速度变化越大。     

一维斜向超声振动辅助磨削滚动轴承钢工艺及试验研究

针对目前只有一维轴向、一维切向等振动方向不变的一维超声振动辅助磨削的情况,首次提出了一维斜向超声振动辅助磨削工艺方法。利用MATLAB对一维斜向超声振动辅助磨削磨粒的运动轨迹进行了模拟分析。建立了超声振动试验系统的动力学模型。通过对超声振动工作台的模态分析,研制了一维斜向超声振动辅助磨削试验系统,对不同角度下超声振动辅助磨削滚动轴承钢的磨削力及表面粗糙度值进行了研究,探究了磨削力及表面粗糙度值随超声振动方向的变化规律。多次试验结果表明,超声振动角度为67.5°附近的表面粗糙度值明显优于其他角度的表面粗糙度值,磨削力也有减小。对正交试验结果的极差分析得出：当超声振动角度为67.5°、砂轮速度为20m/s、工件速度为0.5m/min以及磨削深度为4μm时,加工后的工件表面粗糙度达到最低值,其中工件速度是影响表面粗糙度的最重要工艺参数。     

铣削表面粗糙度在线监测与加工参数的自适应优化

针对实际加工中工件与刀具之间的无规律振动而导致零件表面粗糙度不受控制的问题,提出了一种融合在线监测和自适应加工的方法.以主轴转速、背吃刀量、进给速度以及工件振动量为特征,基于XGBOOST算法对表面粗糙度进行回归分析,建立表面粗糙度的预测模型;在加工中对工件振动量进行实时采集,结合主轴转速、背吃刀量、切削速度和进给量建立实时表面粗糙度在线监测系统;当预测结果超出警戒值时,系统自动对切削参数背吃刀量、切削速度和进给量进行优化,进而减小工件振动,从而保证被加工零件的表面粗糙度.与传统的先加工后测量的方法相比,提出的方法实现了在加工的同时进行预测、分析与切削参数的自适应优化,有效地控制了被加工零件的表面粗糙度.     

铣削表面粗糙度在线监测与加工参数的自适应优化

针对实际加工中工件与刀具之间的无规律振动而导致零件表面粗糙度不受控制的问题,提出了一种融合在线监测和自适应加工的方法.以主轴转速、背吃刀量、进给速度以及工件振动量为特征,基于XGBOOST算法对表面粗糙度进行回归分析,建立表面粗糙度的预测模型;在加工中对工件振动量进行实时采集,结合主轴转速、背吃刀量、切削速度和进给量建立实时表面粗糙度在线监测系统;当预测结果超出警戒值时,系统自动对切削参数背吃刀量、切削速度和进给量进行优化,进而减小工件振动,从而保证被加工零件的表面粗糙度.与传统的先加工后测量的方法相比,提出的方法实现了在加工的同时进行预测、分析与切削参数的自适应优化,有效地控制了被加工零件的表面粗糙度.     

Influence of surface roughness effects on the performance of non-recessed hybrid journal bearings

The effect of journal and bearing surface roughness on the performance of a capillary compensated hole-entry hybrid journal bearing system has been theoretically studied. The analysis considers the average Reynold’s equation for the solution of lubricant flow field in the clearance space of a rough surface journal bearing system. The finite element method and Galarkin’s technique has been used to derive the system equation for the lubricant flow field. The non-dimensional parameters Λ (surface roughness parameter) and γ (surface pattern parameter) have been defined to represent the magnitude of height distribution of surface irregularities and their orientation, respectively. The influence of surface roughness on the bearing performance has been studied for the transverse, isotropic and longitudinal surface patterns. The bearing performance characteristics have been computed for both symmetric and asymmetric capillary compensated hole-entry journal bearing configurations for the various values of surface roughness parameter (Λ), surface pattern parameter (γ) and restrictor design parameter ( ). The computed results indicate that the inclusion of surface roughness effects in the analysis affects the performance of a bearing quite significantly vis-à-vis smooth surface bearing. The study indicates that for generation of accurate bearing characteristic data, the inclusion of surface roughness effects in the analysis is essential.     

Optimisation of machining parameters for turning operations based on response surface methodology

Design of experiments has been used to study the effect of the main turning parameters such as feed rate, tool nose radius, cutting speed and depth of cut on the surface roughness of AISI 410 steel. A mathematical prediction model of the surface roughness has been developed in terms of above parameters. The effect of these parameters on the surface roughness has been investigated by using Response Surface Methodology (RSM). Response surface contours were constructed for determining the optimum conditions for a required surface roughness. The developed prediction equation shows that the feed rate is the main factor followed by tool nose radius influences the surface roughness. The surface roughness was found to increase with the increase in the feed and it decreased with increase in the tool nose radius. The verification experiment is carried out to check the validity of the developed model that predicted surface roughness within 6% error.     

Stability characteristics of rough submerged oil elliptical bearings under dynamic load

This paper discusses the effect of surface roughness on the stability of submerged oil elliptical journal bearings under unidirectional constant and unidirectional periodic load. The non-linear transient simulation, taking the oil film history into account, has been used to predict the threshold of instability. The average flow model of Patir and Cheng (An average flow model for determining effects of three-dimensional roughness on partial hydrodynamic lubrication. Trans. ASME, Journal of Lubrication Technology, 1979, 100, 12–17) has been used to describe the surface roughness effects. The effect of ellipticity ratio and that of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern and variance ratio on the stability has been studied.     

正交车铣TC4钛合金表面粗糙度分析

车铣加工技术是近年发展起来的先进切削加工技术之一。本文采用多因素正交试验法,进行了一系列的正交车铣TC4钛合金切削试验,研究了车铣切削用量与表面粗糙度之间的变化规律。通过方差分析确定了各因素对表面粗糙度的影响大小的主次顺序,每齿进给量和偏心量对表面粗糙度的影响较大。采用回归分析原理,建立了表面粗糙度的预测模型,根据统计检验结果表明,已加工表面粗糙度预测模型呈高度显著检验状态,具有很高的可信度。     

The effect of surface roughness on the vibration behavior of AFM piezoelectric MC in the vicinity of sample surface in air environment based on MCS theory

Recent developments in the field of piezoelectric materials have led to the increasing use of piezoelectric materials in a variety of Atomic Force Microscopy (AFM). Utilizing piezoelectric layer as a sensor and actuator not only reduces the size of microscope but also enhances the quality of surface topography in Micro and Nano scales. In the current study, the effect of surface roughnesson the vibration behavior of AFM piezoelectric micro cantilever (MC) has been investigated in Micro and Nano scales according to the types of the surface roughness. Furthermore, the micro cantilever modelling has been schemed based on the Modified Couple Stress (MCS) theoryin order to model the vibration amplitude of AFM piezoelectric MC that precisely indicates the measured surface roughness. Besides, according to the various modelling of surface roughness, the effect of roughness radius on the minimum and maximum amplitude of Piezoelectric MC has been studied based on the geometry of roughness in air environment. In this environment, the effect of environmental forces including van der Waals, Capillary and contact forces on the vibration amplitude of MC forms the basis of surface topography which has, also, been studied in this article. Moreover, the present study intends to investigate the effect of surface roughness on the vibrating amplitude of MC in both the Tapping and Non-Contact Modes.     

The effect of surface topography on the wear of steel

The pattern of roughness and wear has been obtained by varying the speed, the number of passes and the pre-roughness of the samples in both dry and lubricated sliding conditions. Three-dimensional graphs of wear versus speed versus sliding time and roughness of the worn surfaces were produced and a linear relation between the variation of the roughness and the amount of wear at a high number of passes has been determined. The initial dry wear rate is influenced by the prior surface roughness. In the case of lubricated conditions the influence of prior roughness is not pronounced. In dry sliding the smooth surfaces in the running-in stage roughen and the rough surfaces become smoother, while in lubricated conditions both surfaces become smoother in the first few passes. Sliding perpendicular to the lay produces rougher surfaces and more wear than is the case in the parallel direction.     

The effect of roughness parameter on the performance of hydrodynamic journal bearings with rough surfaces

The influence of the roughness parameter (C) and the roughness patterns (longitudinal, transverse and isotropic) on the steady state and dynamic characteristics of hydrodynamic journal bearings with rough surfaces has been studied using the model of Christensen and Tonder (The hydrodynamic lubrication of rough journal bearings. Trans. ASME, Journal of Lubrication: Technology 1973;95:166–72). Reynolds-type equations have been solved using the stochastic finite method. It is seen that the transverse roughness tends to increase significantly load carrying capacity and stability with roughness values, whereas in the case of other roughness patterns the effect is seen to be very small.     

A note on the homogeneity of the roughness on oblique finish turned surfaces

The homogeneity of the roughness on oblique finish turned surfaces is investigated statistically by an analysis of variance technique applied to experimental data obtained during the useful life of a carbide turning tool. In general, a highly significant row effect (due to tool wear) has been established. A significant column effect has also been found to be present in some of the selected specimens, particularly in those of smaller length. The results of this analysis provide a guide for surface roughness measurements in practice.     

Numerical modelling of surface topography in superabrasive grinding

A numerical simulation technique has been developed to generate the grinding wheel topography using square pyramidal grits. The ground workpiece surface has also been generated simulating the trajectory of all the abrasive grits and removing the interfering material. The average workpiece surface roughness is calculated and the effects of different grinding parameters on the average surface roughness of the generated workpiece have been studied. Finally, the variation of surface roughness with the maximum uncut chip thickness has been studied.     

基于光学色差传感器的表面粗糙度测量

随着机械加工自动化程度的提高，对表面粗糙度的测量提出了越来越高的要求。表面粗糙度的测量一直面临着提高测量精度和抗干扰能力的挑战，提出了一种新的利用光学色差来测量表面粗糙度的非接触测量方法，这一方法不但具有一般非接触测量所具有的快速、对工件表面无损伤等特点，而且在提高精度和抗干扰能力两方面都有很强的优势。重点介绍了利用光学色差法测量表面粗糙度的理论依据以及基于光学色差原理的光学色差传感器，分析了应用光学色差传感器测量表面粗糙度的工作原理。通过实验证明了理论分析与实验结果相符。