Use of surface roughness measurements to improve the estimation of the heat partition in grinding

In grinding, the heat partition is used to estimate the percentage of energy entering the workpiece which makes it possible to estimate grinding temperatures. In this work, a correlation was observed between surface roughness and the heat partition when grinding 1018 steel with an 80 grit aluminum oxide wheel. This correlation was used to improve the usability of a popular heat partition model by making it easier to estimate the grain radius, which is an important parameter in this model. The grain radius is used to account for the grinding wheel surface topography and is virtually impossible to directly measure in practice. To validate the proposed model, infrared temperature measurements along with 3D finite element simulations were used to determine the heat partition for different dressing conditions and techniques. For the experimental conditions used in this research, the measurements and simulations confirmed that one can use surface roughness to estimate the grain radius. The average difference between the heat partition predicted using the proposed model and the conventional approach was 7.5%, while the resulting maximum grinding temperatures predicted using the proposed model agreed with infrared temperature measurements to within 5%.     

基于VC++6.0等间距直线逼近渐开线砂轮修整软件的开发

利用VC++6.0语言为后台程序支撑,研究出等间距的直线逼近渐开线砂轮修整软件。生成软件界面,在界面上可以输入不同的节点,实现不同齿数与模数的齿轮磨削砂轮的修整,并且可以实现动态仿真,生成逼近坐标点。以法向允差ε为精度目标,利用等间距的方式进行直线逼近,得出下一个节点的坐标值,此直线逼近渐开线的算法,其间距相等,使离散点数既满足所需精度要求,又提高了效率。     

基于金刚石微粉烧结棒的超硬砂轮修整试验研究

对金刚石微粉烧结棒修整树脂结合剂金刚石砂轮进行了试验研究.以反映砂轮平面度的端面跳动和径向跳动作为修整效率的评价依据,通过对主轴转速、砂轮组织参数、修整棒进给速度3个方面进行对比试验,得出了以下结论:低主轴转速下修整棒对金刚石砂轮的修整效率较高,砂轮参数对修整效率的影响很小以及修整棒进给速度与修整效率呈非线性关系.     

Experimental study of ELID grinding based on the active control of oxide layer

The oxide layer state directly relates to the grinding efficiency and machining quality in Electrolytic In-process Dressing (ELID) grinding. In order to monitor and control the state of the oxide layer, a new high-frequency pulse power source is proposed for ELID grinding. It uses the superposition of big and small pulses to achieve periodical electrolysis and to adjust oxide layer state. Based on an analysis of current change with duty cycle, a pulse-based fuzzy control program was designed to control the state of the oxide layer within a certain range and the oxide layer grinding efficiency in different oxide layer states was studied. The results show that the new power source could maintain a stable grinding process and that the dressing current should be controlled according to the grinding wheel grain size.     

In-process wire electrical discharge dressing (IWEDD) of metal bonded diamond wheels

Electrical discharge dressing has been established as alternative for conditioning metal bonded diamond wheels, which will be exploited to develop in-process wire electrical discharge dressing (IWEDD). The main requirements for its successful implementation are first presented in this work. Small depth of dressing cuts was found to be feasible and high material removal rates were achieved without damaging diamonds. Dulled grains are finally removed by mechanical contact with the work piece. It was found that grinding forces can be kept constant over time while non-productive time is reduced, showing that IWEDD is a suitable conditioning method with great potential for future industrial applications.     

陶瓷喷涂层精密镜面磨削技术的研究

１陶瓷喷涂层的结构与特性喷涂层在结构上不同于致密的金属材料。在喷涂过程中，被加热至熔化或接近熔化的粉末材料，或者被加热熔化并雾化的丝材颗粒，在高压气流的带动下撞击到基材表面上，产生变形、流散并冷凝成盘状，镶嵌、咬接和填塞到基材表面上。随后喷来的粒子以...     

摩托车发动机铸铝件毛坯的一次性机械清理工艺

从生产实际要求出发，详细介绍了铸件绕冒口机械冲切清理设备与结构布局，模具与工装的设计，并对工艺要点进行了分析。使有证明一次性机械去除代替手工式具有很多优势。     

Dry grinding by special conditioning

Dry grinding is one of the most favourable processes from an economical as well as an ecological point of view. However, it is rather difficult to achieve this goal due to the nature of the grinding process. A common method for reducing and eliminating the use of metalworking fluid is to reduce any harmful heat generation observed in the process. Any change in the grinding parameters such as depth of cut, feed rate, or grinding speed, or the characteristics of the grinding wheel such as grit size, bonding, and porosity, can have a great influence on heat generation. This paper presents some of the very good results of the systematic research works that were done to reduce heat generation by special conditioning using a single-point diamond dressing tool based on the new innovative concept.     

Design specifications in the flowsheet simulation of complex solids processes

In the present work a method for the treatment of design specifications in the simulation of complex solids processes has been developed.Adding a design specification to the flowsheet of a given solids process means that the solid product should fulfill a certain requirement. For example, its Sauter mean diameter should be kept within a certain interval or the mass fraction of particles above a certain threshold should be kept below a certain limit. The method developed here is not only able to handle product specifications but also other stream properties of the process. These properties can be either distributed or concentrated. Even dependently distributed properties e.g. a particle size-dependent contamination can be handled. The treatment of design specifications has been implemented as an extension of the flowsheet simulation system SolidSim.Practical applications of the implemented extension are illustrated with three examples: (i) a simple process for the preparation of brown coal, (ii) a process for the treatment of gravel and sand and (iii) a complex process for the mechanical separation and dewatering of harbor sediments contaminated with heavy metals.     

加蓬Montbeli锰矿深加工利用方向探讨

根据Montbeli锰矿的性质和特点,结合国内多家研究院对该矿所做的相关实验研究,包括原矿性质研究、选矿实验、深加工实验等,探索寻找合理经济的加工方法,探讨矿石的利用方向,为企业如何加工利用该矿石提供参考。