Laser Dressing of Metal Bonded Diamond Wheel

In this study, a laser beam is used as a non-contact thermal dressing tool for a bronze bonded diamond wheel. The pulsed-Nd:YAG laser beam is irradiated on the wheel surface and the bond material partially removed by laser irradiation only. In order to efficiently remove the bond material, it is necessary to direct an air jet on the spot irradiated by the laser so as to blow away the molten binder before it solidifies again. Less damage of diamond particles such as micro-cracks or graphitization occurs. In grinding with a laser-dressed wheel, the grinding forces are almost the same as those for a conventionally dressed wheel. Consequently, effective laser dressing can be expected with the associated dressing conditions.     

Profiled rotary dresser with controlled size and distribution of abrasive grits: Performance assessment

This paper reports on a novel proprietary profiled rotary dresser which, in contrast with conventional tools, enables a controlled arrangement of geometrically defined abrasives over complex profiles. Output forces and abrasives’ wear were investigated during dressing and grinding tests. This showed a significant reduction in radial dressing forces (˜37%) and volumetric loss of material per grit (˜21%) when compared with conventional tools, together with low grinding forces and workpiece surface roughness variability for different wear conditions. The novel dresser proves the ability to obtain uniform wear rates along complex profiles, while allowing abrasive segment replacement to restore the dressing conditions.     

基于数值建模的砂轮形貌仿真与测量

建立球形磨粒在空间随机运动的数学模型,提出创建三维砂轮数值模型的方法。提取仿真砂轮的表层磨粒以生成虚拟砂轮形貌,依据振动模型确定的磨粒中心坐标,将球形磨粒转化为不规则六面体进行统计分析。以单点金刚石笔为修整工具,建立修整模型并将其引入砂轮形貌生成过程之中。利用激光传感器测量实际砂轮形貌的磨粒分布规律,并将试验统计数据与同特征的仿真结果相比较,分析两结果之间的区别和联系。通过计算磨粒突出高度、磨粒间距等评价参数,讨论砂轮形貌修整前后的差异,测量和仿真的结果表明：在初始砂轮形貌中,磨粒突出高度呈正态分布,修整后则近似均匀分布,大部分磨粒间距分布在0.2～0.6 mm,为进一步探讨砂轮形貌对磨削工件的影响提供了依据。     

氧化铜矿石的选矿技术现状与展望

概述了氧化铜矿石资源的特点及矿石性质。分别从浮选工艺、化学浸出工艺和选冶联合工艺3方面总结了氧化铜矿石的选矿工艺研究现状,从直接浮选、硫化浮选、水热硫化浮选、微细粒真空微泡浮选、脱泥浮选等方面详述了浮选工艺的研究进展;介绍了化学浸出工艺（包括酸浸和氨浸两方面）、集常规浮选和浸出工艺各自优点于一身的选冶联合工艺以及氧化铜矿石的微生物浸出、焙烧-氨浸和离析-浮选等新工艺的研究情况。最后指出：提高氧化铜矿石的选矿技术水平必须认真做好矿石的工艺矿物学研究;要加强高效浮选新药剂的研发力度;在确定矿石的处理工艺时,要在充分认识各选矿方法优缺点的基础上进行必要的优化组合,实现各选矿方法的优势互补。     

矽卡岩型透辉石矿选矿试验研究

介绍了新型陶瓷材料-透辉石矿的选矿研究现状,提出采用间接测量酸不溶CaO含量来评价和比较透辉石纯度的检测新方法,对具有代表性的西安里矽卡岩型透辉石矿进行了试验研究。经过弱磁一重选一强磁联合工艺试验,透辉石品位从原矿的40%提高到了80%,达到了透辉石工业使用要求,实现了矽卡岩型透辉石矿的回收利用。     

各民族的面饰风格在文化史进程中是怎样自成一家和转化演变的

在这段《风格》选录中,森佩尔通过对古希腊和其他民族文化的研究,确立了建筑和服饰之间的紧密联系。由此,他提出其著名的"面饰"理论,论证面饰原则对于建筑的重要意义。     

Evaluation of scanning electron microscopy images of a model dressing using image feature extraction techniques and principal component analysis

Twelve dressing systems made by varying protein type, oil level, CaCl₂, NaCl, and sucrose, were examined using scanning electron microscopy. Images from the 12 systems were quantitatively analysed using methods of feature extraction. These methods were based on vectorisations of the images followed by principal component analysis on the extracted vectors. These techniques were used to examine the reproducibility of the acquired images as well as to relate the images to rheologic and sensory texture parameters. Two feature extraction methods were used: the angle measure technique (AMT) and the absolute difference method (ABDF). The ABDF method used fewer principal components to extract information from images relevant to the complex modulus/sensory viscosity of the system, but the information seemed equally well preserved by the two-feature extraction methods. The AMT was more efficient in classifying the images with respect to protein type. A fair correlation between images and complex modulus was obtained (R=0.73). It is suggested that a better correlation might be obtained by adding more systems, increasing the number of areas imaged for each system as well as avoiding systems of low viscosity.     

阳离子捕收剂烷基多胺醚在尖山铁矿的试验研究

通过试验比较了烷基多胺醚系列捕收剂GE-601,GE-610,GE-609,GE-609与十二胺的捕收性能及其泡沫状况,试验结果表明GE-601是理想的阳离子捕收剂。在不添加其他药剂的情况下,用1粗3扫闭路浮选流程处理铁品位为64．53％的尖山铁矿的粗精矿,获得了铁品位为69．41％、回收率为98．42％的优质铁精矿。     

Review of Intelligent Grinding and Dressing Operations

With the increased use of advanced materials, grinding processes become a popular means in the processing of parts, particularly in fabricating products from brittle materials such as ceramics and composites. At present grinding appears to be the only practical and economical means of shaping the parts into the final products with fine surface finish, acceptable surface integrity, and high geometric accuracy (Kovach, J. (1987). Improved grinding of ceramic components. In: Proceedings of the Department of Defence, Machine Tool/Manufacturing Development Conference. AFWAL-TR-4137, Vol. 7, 72-100). In the machining of conventional materials, grinding is also usually used as a finishing operation when high accuracy and surface finish is required, and usually determines the major portion of the processing cost. Despite this importance and popularity, grinding still remains as one of the most difficult to control processes. Unlike machining processes where cutting is performed by a defined single/multiple cutting edge(s), grinding is performed by a number of abrasive grits, which are randomly oriented within a grinding wheel. Therefore, it is impossible to maintain or control the shape of these hard grits, which are active in the cutting process (Malkin, S. (1989). Grinding Technology, Theory and Applications of Machining with Abrasives, Chister, England: Ellis Horwood Limited; Okafor, A. C., Marcus, M., Tipirneni, R. (1990). Multiple sensor integration via neural networks for estimating surface roughness and bore tolerance in circular end milling. Transaction of NAMRI/SME 128-136). Grinding is a very complicated process, consisting of complex interactions between a large numbers of variables. These variables can be grouped into four major categories: (a) machine tool, (b) workpiece material, (c) grinding wheel, and (d) operating parameters (Allor, R. L. Whalen, T. J., Baer, J. R., Kumar, K. V. (1993). Machining of silicon nitride: experimental determination of process/property relationships. In: Proceedings of the International Conference on Machining of Advanced Materials. Washington, DC, 223-234; Lezanski, P., Rafalowicz, J., Jedrzejewski, J. (1993). An intelligent monitoring system for cylindrical grinding. Annals of the CIRP 42(1):393-396; Li, K., Liao, T. W. (1997). Modelling of ceramic grinding processes, number of cutting points and grinding forces per grit. Journal of Materials Processing Technology 65(1-3):1-10). The dressing and truing processes used to prepare the wheel have an important effect on the grinding wheel variables and consequently on the output of the grinding process. To achieve this understanding, many researchers focused on the modeling of grinding processes. Some of these models are completely theoretical, and others are practical with theoretical explanations and empirical equations. The aim of this research was to find the relationship between the process variables, the process parameters, and workpiece quality. This review presents the theoretical and experimental models used, process design algorithms, expert systems, artificial intelligent algorithms, fuzzy logic and neural network algorithms, process monitoring and control, and in particular artificial intelligence control systems.     

数控编程容易实现的新型砂轮修整器

介绍一种新型的数控磨床砂轮修整器，它具有2移动轴 1转动轴的三轴联动功能，因此能精确修整各种曲面的砂轮；而且它的修整工具能绕修整工具刀口的圆弧圆心转动，可不考虑绕转动轴的转动对2移动轴的影响，故数控编程容易实现。该修整器已获专利授权。