Modeling surface roughness in the stone polishing process

In this paper, a new method for modeling and predicting the surface roughness of the workpiece in the stone polishing process is developed. This method is based on the random distribution of the stone grain protrusion heights and the force balance by contact grains. To do so, first, the topography of a polishing stone is generated based on a Gaussian distribution with the mean value and standard deviation determined from a given stone grit number. Second, the plasticity theory is applied to determine the micro depth of cut of a single grain for a given workpiece hardness (Brinell number). Third, a search method is developed to determine the number of the contact grains and the micro depth of cut, based on the force balance principle between the force applied on the stone and the forces transmitted to the grains that are in contact with the workpiece. Fourth, a method is presented for predicting the surface roughness based on the micro depth of cut and contact grains. A good agreement of the prediction results with the experimental data proves the effectiveness of the proposed method.     

Mathematical model determination for improvement of surface roughness in magnetic-assisted abrasive polishing of nonferrous AISI316 material

The new magnetic-assisted abrasive polishing process for non-ferrous materials was proposed in order to increase the magnetic flux density which directly influences the contact force between the workpiece and the abrasives.The permanent magnets were installed under the workpiece and their effects were verified by the experiments.The effect of polishing factors on the improvement of surface roughness was evaluated based on the Taguchi experimental method,and the optimal conditions for polishing AISI316 stainless steel were determined.The predicting model for improving surface roughness was developed and the validity of the developed model was tested.The results show that the permanent magnets are very useful in improving the surface roughness in the magnetic-assisted abrasive polishing process.     

基体表面粗糙度对镀硬铬层零件镜面抛光的影响

机械电解镜面抛磨镀硬铬层轴类零件时，通常从电、液参数以及工件、工具转速等着手，优选出最佳参数。但从实验中发现，零件基体表面粗糙度对抛光效果有着非常重要的影响，甚至决定抛光的成败。通过大量的对比试验和观察发现：零件基体表面粗糙度越小，抛光效果越好；反之，则差。     

Non-abrasive polishing of glass

Supersmooth surfaces are often needed in high- and new-technology products. The traditional polishing method to obtain supersmooth surfaces is abrasive polishing. In this paper, a new kind of polishing method, non-abrasive polishing (NAP), is presented. The polishing wheel of NAP is made of ice that is frozen deionized water, so there is no abrasive in the polishing wheel. Compared with traditional polishing methods, NAP can obtain Ångström-order surface roughness values free from microscratches and subsurface cracks. Based on adhesion theory, the material removal mechanism of NAP is presented in the paper. The paper also analyzes the polishing equipment and processing technique of NAP. The best surface roughness, R_a=0.48 nm, of K9 glass is obtained using NAP. According to the relationship between surface roughness and adhesion, the surface roughness fluctuation phenomenon is explained in the paper. The surface roughness fluctuation phenomenon is expected to be avoided by measuring the fractal dimension of the polished surface.     

固结磨料研磨K9玻璃表面粗糙度模型修正

考虑磨粒轨迹和研磨垫弹性的影响,分析磨粒间距的概率密度函数,计算磨粒轨迹重叠率;引入与研磨参数相关的修正因子,并确定其值,修正固结磨料研磨K9玻璃表面粗糙度公式,实验验证修正模型。结果表明:修正后,K9玻璃表面粗糙度模型计算值与实验值误差控制在4%以内。显著提高K9玻璃表面粗糙度的预测精度,有效指导其研磨方案设计,提高加工效率。     

金刚石砂轮磨削铁氧体的表面粗糙度与形貌分析

本文研究了树脂结合剂金刚石砂轮磨削铁氧体材料时,磨削深度、工件进给速度对磨削表面粗糙度和材料去除方式的影响规律,以此探索提高铁氧体磨削表面质量的有效途径。采用单因素法设计试验方案对铁氧体进行磨削,测量表面粗糙度数据并对其进行方差分析,对铁氧体磨削表面形貌进行观察。结果表明：随着磨削深度、工件进给速度的增加,表面粗糙度值升高,同时表面塑性痕迹减少,脆性断裂痕迹增加,且磨削深度对表面粗糙度的影响要比工件进给速度的更显著,因此,制定磨削工艺时,考虑到粗磨为了提高效率,降低表面损伤,优化得到磨削工艺为磨削深度5μm,工件进给速度10 m/min;精磨为了获得较低的表面粗糙度,采用磨削深度5μm、工件进给速度为5 m/min,可以提高磨削表面延展性。     

A genetic algorithmic approach for optimization of surface roughness prediction model

Due to the widespread use of highly automated machine tools in the industry, manufacturing requires reliable models and methods for the prediction of output performance of machining processes. The prediction of optimal machining conditions for good surface finish and dimensional accuracy plays a very important role in process planning. The present work deals with the study and development of a surface roughness prediction model for machining mild steel, using Response Surface Methodology (RSM). The experimentation was carried out with TiN-coated tungsten carbide (CNMG) cutting tools, for machining mild steel work-pieces covering a wide range of machining conditions. A second order mathematical model, in terms of machining parameters, was developed for surface roughness prediction using RSM. This model gives the factor effects of the individual process parameters. An attempt has also been made to optimize the surface roughness prediction model using Genetic Algorithms (GA) to optimize the objective function. The GA program gives minimum and maximum values of surface roughness and their respective optimal machining conditions.     

K9玻璃磁性研磨抛光表面粗糙度试验研究

针对K9光学玻璃研磨抛光过程中存在的问题,将磁性研磨加工方法应用在光学玻璃的研磨抛光上。试验表明,K9玻璃的表面粗糙度值Ra由原来的90nm左右下降到40nm左右。为进一步研究磁性研磨试验的4个因素,设计了正交试验,最终得出各个因素对于工件表面粗糙度影响的主次顺序,并确定其最优组合为:磁极转速2300r/min,加工间隙1.5mm,磁感应强度0.4T,进给速度200mm/min。     

聚晶金刚石表面粗糙度灰色组合预测模型

基于金刚石木工刀具电火花磨削的特点,采用灰色系统理论建立了聚晶金刚石表面粗糙度灰色组合预测模型,该模型为多元线性回归模型的一种改进模型。通过聚晶金刚石电火花磨削工艺参数正交设计实验进行了验证,实验结果表明:该模型能够较好地预测出聚晶金刚石的表面粗糙度,预测最大误差为8.67%,能达到工程实际要求。     

断口轮廊迹线法测定玻璃/环氧复合材料断面粗糙度

运用轮廓迹线法测定了玻璃/环氧复合材料三点弯曲试样断面轮廓线粗糙度参数R_L及断裂能与断口表面粗糙度参数R_s的关系,实验结果指出:断面轮廓线粗糙度与填料成份、断裂性质等因素有关,与断裂能呈近似线性关系;韧断时测量值偏小,脆断时偏大,填料成份、断裂机制相同时吻合得好。     

表面改性碳化硅在玻璃磨边金刚石抛光砂轮(UPR)上的应用

采用高分子表面活性剂对碳人硅进行表面改性制备出了弹性微球复合粒子，降低了微粉的表面能，提高了与金刚石及结合剂的粘结性能，并通过加入柔性剂对不饱和聚酯树脂增韧改性，研制出了UPR玻璃磨边金刚石抛光砂轮。实验证明其抛光效果和使用寿命均达到了同类进口产品的水平，且生产工艺简单，设备投资成本低，无污染。     

A predictive surface profile model for turning based on spectral analysis

This article presents a predictive approach of surface topography based on the FFT analysis of surface profiles. From a set of experimental machining tests, the parameters investigated are: feed per revolution, insert nose radius, depth of cut and cutting speed. The first step of the analysis consists of normalizing the measured profiles with the feed per revolution. This results in normalized profiles with a feed per revolution and a signal period equal to 1. The effect of each cutting parameter on the surface profile is expressed as a spectrum with respect to the period length. These effects are quantified and can be sorted in descending order of importance as feed per revolution, insert nose radius, depth of cut and cutting speed. The second part of the paper presents a modeling of the surface profile using the parameters effects and one interaction. The proposed model gives the spectrum of the profile to be predicted. The inverse Fourier transform applied to the spectrum yields the expected surface profile. Measured and simulated profiles are compared for two cutting conditions and results correlate well.     

陶瓷结合金刚石砂轮磨削硬质合金表面粗糙度的研究

本文采用正交试验法研究了砂轮线速度、横向进给速度、磨削深度和磨削行程四种磨削参数对陶瓷结合金刚石砂轮磨削硬质合金表面粗糙度的影响,通过显微镜观察了硬质合金的表面加工质量,分析了影响表面加工质量的因素,得出了优化的工艺参数.结果表明:四种磨削参数对硬质合金表面粗糙度的影响顺序为:横向进给速度＞砂轮线速度＞砂轮行程＞磨削深...     

Study on surface roughness model and surface forming mechanism of ceramics in quick point grinding

The quick-point grinding experiment of fluorophlogopite was conducted by using a MK9025A profile grinder which considered the simple single factor, such as the grinding wheel and table feed speed, grinding depth, inclining angle and deflection angle. The experimental results indicated that the surface roughness was mainly influenced on inclining angle and deflecting angle. Moreover, the modified model of the quick-point grinding process was proposed in the paper, which based on Malkin kinematics model, Snoeys empirical model and grinding thickness empirical model. The inclining angle and deflecting angle was introduced in the modified model. Comparison of the predicted results of these models and experimental ones indicated that the modified model was in well agreement with the experimental data. Further, standard deviation of these models and experiment was studied in the paper, it is found that the modified model was the more ideal. In order to study the effect of various technology factors on the sensitivity of surface roughness, “Relative extremum error” concept was first proposed in the paper. It was found that simple single factor in the modified model were relatively sensitive to surface roughness than other models.     

A review of surface roughness generation in ultra-precision machining

Ultra-precision machining (UPM) is capable of manufacturing a high quality surface at a nanometric surface roughness. For such high quality surface in a UPM process, due to the machining complexity any variable would be possible to deteriorate surface quality, consequently receiving much attention and interest. The general factors are summarized as machine tool, cutting conditions, tool geometry, environmental conditions, material property, chip formation, tool wear, vibration etc. This paper aims to review the current state of the art in studying the surface roughness formation and the factors influencing surface roughness in UPM. Firstly, the surface roughness characteristics in UPM is introduced. Then in UPM, a wide variety of factors for surface roughness are then reviewed in detail and the mechanism of surface roughness formation is concluded thoroughly. Finally, the challenges and opportunities faced by industry and academia are discussed and several principle conclusions are drawn.     

A deterministic interfacial cyclic oxidation spalling model

A series summation has been developed to model the iterative scale growth and spalling process of cyclic oxidation. Parabolic scale growth has been assumed. Interfacial spallation of a constant area fraction was stipulated to occur only at the thickest portions. Inputs are the parabolic growth rate constant, spall area fraction, oxide stoichiometry, and cycle duration. Outputs include the net weight change, amount of oxygen and metal consumed, and amount of oxide spalled. Classic weight change curves are produced with an initial maximum and final linear weight loss rate. This simplicity allowed for representation by explicit algebraic functions for all outputs and characteristic features. The maximum in weight change varies directly with the parabolic rate constant and cycle duration and inversely with the spall fraction, all to the ¹/₂ power. The ratio of the number of cycles to reach maximum and zero weight change is exactly 1:3, and these vary only with the inverse of the spall fraction. Many similarities to and some differences with previous cyclic models are identified.     

微粉金刚石钎焊砂轮磨削氧化铝陶瓷的磨削力和表面粗糙度特征

在不同磨削深度、砂轮转速和进给速度组合下,研究微粉金刚石钎焊砂轮磨削氧化铝陶瓷过程的磨削力及工件的表面粗糙度的变化规律,并筛选出低磨削力和低工件表面粗糙度的加工工艺参数。试验结果表明:在微粉金刚石钎焊砂轮的磨削过程中,氧化铝陶瓷主要通过脆性断裂的方式去除;随着磨削深度、进给速度的增加,砂轮在进给方向和切深方向的力以及工件表面粗糙度都上升;随着砂轮转速的增加,进给方向和切深方向的力以及工件表面粗糙度都下降。试验获得的低磨削力和低工件表面粗糙度精密加工工艺参数分别为:磨削深度为1.0 μm,进给速度为12 mm/min,砂轮转速为24 000 r/min和磨削深度为1.0 μm,进给速度为1 mm/min,砂轮转速为20 000 r/min。低磨削力磨削时,微粉金刚石钎焊砂轮受到的X方向和Z方向的磨削力分别为0.15 N和0.72 N;精密加工后的氧化铝陶瓷的表面粗糙度值可达0.438 μm。      

Relationship between surface roughness and subsurface crack depth during grinding of optical glass BK7

Subsurface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the depth of subsurface cracking through the measurement of surface roughness under different grinding parameters. Based on the features of surface and subsurface cracks as well as the kinetic analysis of surface grinding, the relationship between surface roughness and subsurface crack depth was established. Surface grinding experiments for optical glass BK7 were conducted. Utilizing optical microscope, optical profiling system and polishing-etching technique, the dependence of surface roughness and subsurface crack depth on grinding parameters was systematically analyzed. The predicted model of the relationship between surface roughness and subsurface crack depth was compared with experimental results. It was found that the relationship between surface roughness and subsurface crack depth is influenced by the half apex angle of abrasive grain as well as the magnitude of extra grain extrusion.     

Optimization of feedrate in a face milling operation using a surface roughness model

Optimization of feedrate is valuable in terms of providing high precision and efficient machining. The surface roughness is particularly sensitive to the feedrate and the runout errors of the inserts in a face-milling operation. This paper analyzes the effects of the insert runout errors and the variation of the feedrate on the surface roughness and the dimensional accuracy in a face-milling operation using a surface roughness model. The validity of the developed model was proved through cutting experiments, and the model was used to predict the machined surface roughness from the information of the insert runouts and the cutting parameters. From the estimated surface roughness value, the optimal feedrate that gave a maximum material removal rate under the given surface roughness constraint could be selected by a bisection method.