金刚石砂轮表面形貌测量系统

为了实现对金刚石砂轮表面形貌的非接触精密测量,开发了基于干涉原理的金刚石砂轮表面形貌专用测量系统,研究了该系统的测量原理和关键技术。根据垂直扫描白光干涉显微测量原理以及被测对象的特征,提出了适用于砂轮测量的方法,研究了系统的自动扫描范围、垂直方向的扫描方法、单次测量三维表面的恢复算法和磨粒的识别算法。结合自行设计的夹具搭建了砂轮测量系统,并对多次测量拼接算法进行了实验分析。实验结果表明:基于区域重合大小(重合度为30%~50%)的拼接算法获得的拼接前后重合区域的相关系数均大于0.8,拼接后重合区域的高度差均小于0.4μm。得到的结果显示所搭建的系统可以恢复砂轮的形貌,其测量范围和精度满足砂轮磨粒评定和分析的要求。     

The application of 3D-motif analysis to characterize diamond grinding wheel topography

The extraction of protruding diamond grains feature from the measured data of grinding wheels is the key to assessing their surface texture and predicting their functional performance. The 3D-motif analysis was utilized to identify the significant features. Based on 6-neighbourhood and wolf pruning, the tiny and insignificant motifs were eliminated and the surface of grinding wheel was segmented into large significant motifs. Four surface samples of #600 diamond grinding wheel were measured by using Alicona Infinite Focus Measuring Instrument and analyzed based on 3D-motif method. As the results shown, the 3D-motif analysis provided an effective method to segment the measured surface into significant features. The experiments also indicated that wolf pruning at 5% produced a proper count of the protruding grains extracted from grinding wheel surface.     

金刚石微粉砂轮超精密磨削技术

论述了金刚石微粉砂轮超精密磨削的特点、存在的技术难题及其发展前景。对金刚石微粉砂轮超精密磨削机理进行了探讨，认为它是以微切削为主的多种作用的融合；研究了金刚石微粉砂轮修整机理及其常用的有效修整方法；提出了树脂-金属复合结合剂金刚石微粉砂轮的构想，论述其结构的形成、制作过程及其实际磨削效果；最后，探讨了进行金刚石微粉砂轮超精密磨削时的影响因素及环境条件。     

圆弧砂轮的修整和金刚笔的调整方法

介绍了磨削球轴承沟道用砂轮的修整方法及修整砂轮圆弧所用金刚笔的不同调整方法,对保证和提高球轴承沟道磨削质量和加工效率具有借鉴作用。     

Recognition of diamond grains on surface of fine diamond grinding wheel

The accurate evaluation of grinding wheel surface topography, which is necessary for the investigation of the grinding principle, optimism, modeling, and simulation of a grinding process, significantly depends on the accurate recognition of abrasive grains from the measured wheel surface. A detailed analysis of the grain size distribution characteristics and grain profile wavelength of the fine diamond grinding wheel used for ultra-precision grinding is presented. The requirements of the spatial sampling interval and sampling area for instruments to measure the surface topography of a diamond grinding wheel are discussed. To recognize diamond grains, digital filtering is used to eliminate the high frequency disturbance from the measured 3D digital surface of the grinding wheel, the geometric features of diamond grains are then extracted from the filtered 3D digital surface, and a method based on the grain profile frequency characteristics, diamond grain curvature, and distance between two adjacent diamond grains is proposed. A 3D surface profiler based on scanning white light interferometry is used to measure the 3D surface topography of a #3000 mesh resin bonded diamond grinding wheel, and the diamond grains are then recognized from the 3D digital surface. The experimental result shows that the proposed method is reasonable and effective. __________ Translated from Journal of Dalian University of Technology, 2007, 47(3): 358–362 [译自: 大连理工大学学报]     

Recognition of diamond grains on surface of fine diamond grinding wheel

The accurate evaluation of grinding wheel surface topography, which is necessary for the investigation of the grinding principle, optimism, modeling, and simulation of a grinding process, significantly depends on the accurate recognition of abrasive grains from the measured wheel surface. A detailed analysis of the grain size distribution characteristics and grain profile wavelength of the fine diamond grinding wheel used for ultra-precision grinding is presented. The requirements of the spatial sampling interval and sampling area for instruments to measure the surface topography of a diamond grinding wheel are discussed. To recognize diamond grains, digital filtering is used to eliminate the high frequency disturbance from the measured 3D digital surface of the grinding wheel, the geometric features of diamond grains are then extracted from the filtered 3D digital surface, and a method based on the grain profile frequency characteristics, diamond grain curvature, and distance between two adjacent diamond grains is proposed. A 3D surface profiler based on scanning white light interferometry is used to measure the 3D surface topography of a #3000 mesh resin bonded diamond grinding wheel, and the diamond grains are then recognized from the 3D digital surface. The experimental result shows that the proposed method is reasonable and effective.     

金刚石滚轮修整器的设计及磨削方式

金刚石滚轮是新兴的砂轮修整工具,可以修整出各种复杂形面。介绍金刚石滚轮修整器的设计原理及磨削方式。     

Modeling and simulation of grinding surface topography considering wheel vibration

Grinding is an important means of realizing precision and ultra-precision machining. Vibration caused by an unbalanced grinding wheel in grinding process has a significant impact on the quality of workpiece surface. However, the effect of wheel surface topography and/or the relative vibration between grinding wheel and workpiece are not considered in most researches. Taking the relative vibration between grinding wheel and workpiece into account, alongside the abrasive grain trajectory equation, a new analysis and simulation model for surface topography of the grinding process is established. The model for the topography of the grinding wheel surface is first studied, and subsequently, a new simulation model for surface topography of the grinding process is proposed. Case studies are performed at the end, and the influence of grinding wheel vibration amplitude, wheel grit number, as well as grinding parameters on the surface waviness and roughness is discussed. The simulation results could be used to optimize the actual grinding process to improve the ground surface quality or predict the surface topography by given grinding parameters.     

Wear of diamond grinding wheel in ultrasonic vibration-assisted grinding of silicon carbide

It is recognized that grinding efficiency and ground surface quality are determined by grinding wheel performance. Additionally, the investigation on wear behavior is essential for evaluating the grinding wheel performance. There is a lack of research on the tool wear behavior during ultrasonic vibration-assisted grinding (UAG), whose grain motion trajectory differs from that in conventional grinding (CG). In the present work, CG and UAG tests of silicon carbide (SiC) were conducted in order to investigate the effects of ultrasonic vibration on the tool wear through tracking observation of grains. Meanwhile, the grinding forces and ground surface roughness correlated to the tool wear stages were studied. The results demonstrated that the main wear types during UAG were micro-fracture and macro-fracture which caused the wheel sharpening, while during CG, the main wear type was attritious wear that made the wheel blunt. As a result, UAG obtained lower and more stable grinding forces while slightly rougher ground surface in comparison with CG.     

Grinding of brittle materials with brazed diamond grinding wheel

Brazed diamond grinding tool is the most promising tool, which is fitter for powerful and high-efficiency grinding and may be the substitute of plated one in the future. But the research of the tool on brittle material grinding is still few. In the paper, it has been proved that the tool can achieve much better surface quality than any other tools, though large grit size is used in the tool fabrication. Analysis shows that most brittle material surface quality can be improved with the decrease of depth of cut of single grit, but they cannot be improved further because of some unavoidable surface defects.     

基于双目图像的砂轮地貌检测

砂轮地貌的准确检测可以反映砂轮磨粒的出露高度和分布情况等,对于揭示砂轮的磨削机理发挥重要的作用.鉴于传统的砂轮地貌检测方法存在种种缺陷,提出了一种基于双目图像的磨粒出露高度检测方法.该方法采用灰度模板匹配算法,通过优化模板尺寸进行图像匹配,可以估算出磨粒的出露高度.试验结果令人满意,磨粒出露高度估算误差小于5%.     

多晶体金刚石磨轮磨削光学玻璃的研究

采用冲击压缩法(Shock Compression Method,SCM)合成的多晶体金刚石磨粒,设计磨削光学玻璃的实验装置.实验结果表明,采用该方法磨削光学玻璃,与单晶体金刚石磨粒磨削光学玻璃相比,采用多晶体金刚石磨粒加工光学玻璃能得到良好的加工表面.     

Reduced models of grinding wheel topography and material removal to simulate dynamical aspects in grinding

Increasing competition and short product life cycles make it necessary to optimize and evaluate the outcome of manufacturing processes. In tool grinding, models for the final workpiece geometry and cutting forces are of particular interest. To establish a valid general grinding model, we investigated the cutting process and the influence of local grinding wheel engagements on the material removal. We consequently developed models of material removal and grinding wheel topography, which capture the main correlations in grinding. In combination, temporal cutting forces and final workpiece geometry are predictable and are in excellent agreement with experimental data. The introduced models are valid for grinding in general, since they are solely based on the geometry and process parameters, and hence are applicable for manufacturing process optimization.     

多颗粒金刚石小砂轮的耗损规律研究

多颗粒金刚石小砂轮轴向进给磨削能实现工程陶瓷等硬脆材料的高效加工,横向裂纹和中位裂纹的扩展均产生材料的去除.通过对多颗粒金刚石小砂轮结构和实验方案设计,能更好地研究端面边缘金刚石对陶瓷加工过程的影响及金刚石的磨损规律.还利用边缘检测和轮廓曲线拟合的方法来实时追踪检测金刚石顶尖曲率半径变化来研究金刚石颗粒的耗损规律,实验结果证明:磨粒顶锥角越大,金刚石磨粒磨削行程越长;材料磨削深度与进给速度两加工参数越大,磨削力和磨削温度越高,金刚石颗粒磨削行程越短.     

Form-truing error compensation of diamond grinding wheel in CNC envelope grinding of free-form surface

In computer numerical control (CNC) grinding of free-form surface, an ideal arc profile of trued diamond grinding wheel is generally employed to plan 3D tool paths, whereas its form-truing errors greatly influence the ground form accuracy. A form-truing error compensation approach is proposed by using an approached wheel arc profile to replace the previously designed ideal one. The objective is to directly compensate the trued wheel arc-profile errors. It may avoid the time consumption of traditional approach that compensates the measured coordinate point errors of workpiece to an iterative grinding operation. First, the 3D tool path surface was constructed to plan the 3D tool paths. Second, the CNC arc truing of grinding wheel was conducted to analyze the form-truing error distribution relative to the applied wheel arc profile. Then, the form-truing error compensation was carried out in CNC envelope grinding. Finally, the iterative closest point (ICP) algorithm was used to match the measured coordinate points of workpiece to ideal free-form surface. It is shown that the 3D tool path surface constructed is practicable to plan arbitrary 3D tool paths for the form-truing error compensation. The ICP matching may be used to investigate 3D ground form error distribution. It is confirmed that the form-truing error compensation can directly improve the 3D ground form accuracy. It may decrease the 3D ground form error by about 20% when the 2D form-truing error is reduced by about 58% using the same truing conditions for CNC grinding.     

Effects of dressed wheel topography on patterned surface textures and grinding force

The camshaft is a crucial component of an engine’s valve train. This paper devotes to the experimental studies of the performance of laser surface textured (LST) camshaft. The first part experiment was carried out on the block-on-ring tester to investigate the tribological behaviors of textured surface in line contact. The area density of the textured dimples was in the range 3–40% with depths 5–24 μm and diameter 70 μm. The friction coefficient and wear tracks were analyzed to confirm the optimum textured patterns. After that, the local LST cams (textured on the lifting region) were further tested in a single-cylinder diesel. It was found that after 300 h durability test at the rated speed and load, the total lifting loss of cams decreased nearly 34.4% in maximum. In addition, the performance of the engine was not affected evidently. The enhanced lubricity and local hardening were two mechanisms for highly promoting the anti-wear property of the LST cams.     

高速钢材料的粗金刚石砂轮轴向进给数控磨削机理研究

根据正交试验确定了影响高速钢材料的粗金刚石砂轮轴向进给数控磨削表面粗糙度值Ra的最主要因素是进给速度Vf.在此基础上,进行进给速度Vf单因素数控磨削实验,对数控磨削后表面粗糙度值进行了分析.     

Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 μm grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope. The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential of super abrasive diamond wheels in ductile machining brittle materials. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 95–101 [译自: 机械工程学报]