综观CBN磨削技术

CBN砂轮磨削正在逐渐推广,尤以日本、欧洲与美国使用较多。本文综合分析了CBN磨削的优点、成本、需要具备的条件、采用的机床以及砂轮型式和适用范围等,对我国推广CBN磨削很有参考价值。     

基于Shannon熵与声发射信号的CBN砂轮性能监测方法研究

为了在磨削加工过程中能够有效判别CBN(Cubic Boron Nitride)砂轮的磨削性能,提出了一种基于Shannon熵理论与声发射信号的CBN砂轮性能监测方法。首先,利用声发射传感器采集CBN砂轮磨削加工过程中的声发射信号,基于最大信息熵对CBN砂轮磨削加工过程中的声发射信号进行概率密度估计,获得磨削加工过程中声发射信号的最大熵概率密度分布。然后,通过分析研究CBN砂轮在修整过后循环磨削以及不同直径剩余磨削时的声发射信号特征,根据交叉熵原理分析CBN砂轮不同磨削性能时声发射信号最大熵概率密度分布,并通过设定交叉熵阈值来辨别磨削加工过程中CBN砂轮的磨削性能。最后,为验证该方法的实用性,在某工厂CBN砂轮磨削产品生产线上进行大量实验研究,结果表明,该方法对CBN砂轮磨损状态及CBN砂轮剩余寿命进行有效监测,验证了该方法监测CBN砂轮在磨削加工过程中磨削性能的有效性。     

CBN砂轮用于齿轮的精密加工

以往,齿轮磨床一般都使用氧化铝(Al_2O_3)砂轮。自美国通用电气公司向世界推出该公司所合成的立方晶体氮化硼(CBN)以来,对用CBN作为磨粒的砂轮在进行钢件的平面磨削和圆柱磨削方面所显示出的极佳的锋利度和耐磨耗性已为各国众多的研究人员所确认。为此,CBN砂轮又被用于齿轮的磨削加工。最近,一些机床厂家以有效利用CBN砂轮的特性为目的而开发出了有一定特色的齿轮磨床。如马格公司新开发的使用CBN砂轮用于加工轧机齿轮轴的立式磨齿机,由于使用了CBN砂轮使过去的干磨改为生产率高的湿磨。又如格里森公司开发的使用碗形CBN砂轮的螺旋锥齿轮穑准双曲线锥齿轮磨齿机,在几分钟     

陶瓷结合剂CBN砂轮对45淬硬钢的磨削研究

用陶瓷结合剂CBN砂轮对45淬硬钢工件进行磨削试验，对磨削过程中CBN砂轮的磨损和磨削比进行了研究，发现了陶瓷缝合剂CBN砂轮的磨损特征。     

电镀CBN锥砂轮磨削齿面残余应用的研究

从磨削表面生成过程出发,对电镀CBN锥砂轮磨齿表面残余应力进行了定性分析,并对其与陶瓷CBN锥砂轮在不同工艺参数组合下磨削后齿面残余应力状态做了对比试验。结果表明,电镀CBN锥砂轮磨削后齿面处于残余应力状态,且在相同金属去除率时电镀CBN锥砂轮比陶瓷CBN锥砂轮磨削后齿面的残余压应力值更大。     

CBN砂轮高效磨削系统的优化

CBN磨削问世以来，CBN砂轮在磨削加工中迅速得到广泛应用。在不久的将来，现在使用的普通磨料将会有2／3为CBN磨削所代替，1／3为SG磨料超细晶粒结构高纯度氧化铝）所代替。这种发展趋势应引起磨削加工行业的重视。更加全面深入地研究CBN砂轮在摩削加工中的应用已势在必行。一、CBN砂轮高效磨削系统使从CBN砂轮进行高效磨削，在国内目前还仅限于难加工材料的磨削加工，作为一个较新的应用研究领域，人们对它的认识更显不足。国内外许多学者曾从各个不同的方面对CBN砂轮磨削进行了深入细致的研究，但全面系统地对CBN砂轮的应用研…     

电镀 CBN 锥砂轮磨削齿面残余应力的研究

从磨削表面生成过程出发,对电镀CBN锥砂轮磨齿表面残余应力进行了定性分析,并对其与陶瓷CBN锥砂轮在不同工艺参数组合下磨削后齿面残余应力状态做了对比试验。结果表明,电镀CBN锥砂轮磨削后齿面处于残余压应力状态,且在相同金属去除率时电镀CBN锥砂轮比陶瓷CBN锥砂轮磨削后齿面的残余压应力值更大。     

模块化的宙斯磨床

由于现代工业产品的更新速度加快,要求机床降低加工成本,缩短产品加工链,增加加工柔性。宙斯磨床正是根据此要求进行开发的。该产品采用先进的模块化结构,在CBN砂轮磨削外圆和非圆领域可为用户提供最佳的解决方案。磨削方式宙斯磨床可采用普通砂轮、CBN砂轮和金刚石砂轮完成:※     

磨削钛合金用陶瓷CBN砂轮的研制

阐述了磨削钛合金用陶瓷结合剂CBN砂轮的研制：主要有结合剂体系的选择，CBN砂轮浓度的选择，填充剂选择，还研究了磨削时砂轮线速度对磨削效果的影响。研究试验结果表明，磨削钛合金时CBN砂轮的浓度应在125％左右，浓度太高或太低都会使磨削成本增加；填充剂应选用碳化硅而不用CBN砂轮常用的氧化铝；磨削时砂轮线速度应在45m／s以上。这些结果可作为选用陶瓷CBN砂轮磨削钛合金时的参考。     

国产陶瓷结合剂 CBN砂轮磨削45淬硬钢的试验研究

通过采用国产陶瓷结合剂CBN砂轮对45淬硬钢工件进行磨削试验，系统分析了磨削参数对CBN砂轮磨损的影响，获得了能够进行高速高效磨削的合理磨削参数。     

砂轮线速度对CBN砂轮磨损影响的磨削试验研究

通过用陶瓷结合剂CBN砂轮对45淬硬钢工件进行磨削试验，深入分析了砂轮线速度对砂轮磨损的影响，获得能够进行高速高效磨削的合理砂轮线速度。     

A precision grinding method for screw rotors using CBN grinding wheel

Aiming at the high precision machining of screw rotors, a new grinding method for screw rotors using cubic boron nitride (CBN) grinding wheel is presented in this paper. Small electroplated CBN grinding wheel is firstly used to grind screw rotors. The mathematical model for the axial profiles of CBN grinding wheel is developed based on gear engagement theory. Taking the backlash of screw rotors and the coating thickness of CBN layer into consideration, the modification of the base body of the wheel shape is introduced into the design of the CBN grinding wheel. Wire cut electrical discharge machining low speed (WEDM-LS) was used to machine the base body of the CBN grinding wheel. The formed turning tools of the base body of CBN grinding wheel using WEDM-LS and the wheel shapes of CBN grinding wheel using the formed turning tool were performed. The CBN grinding wheels for the screw rotors were made to verify the validity and effectiveness of the presented method. The electroplated CBN grinding wheels were used to machine the screw rotors, and the machining experiments were performed. The data obtained in the experiments reach the fifth class of Chinese Standard GB10095-88.     

SEM observations of the sliding behavior of A12O3 and CBN against steel

Both aluminum oxide (A1₂O₃) and cubic boron nitride (CBN) are being used as the abrasive medium in grinding wheels. To compare the effectiveness of these abrasives, a study was made, using the scanning electron microscope (SEM), to observe the sliding behavior and surface damage resulting from single particles of polycrystalline A1₂O₃ and CBN sliding dry against hardened M-50 tool steel. These experiments were run in the chamber of the SEM, which permitted direct observation of the contact areas at high magnifications. Friction force was monitored and videotape recordings were made continuously during these tests. Significantly lower friction and smoother wear tracks were obtained with the CBN. The A1₂O₃ grit produced much sharper ridges and considerable microcracking on the ridges. These microcracks were formed perpendicular to the wear track. The wear tracks obtained in the SEM were compared with the surfaces produced by surface grinding hardened steel with both CBN and A1₂O₃ wheels. At high magnifications, marked similarities between the ground surfaces and the surfaces produced by the basic sliding tests were noted. It is suggested that because of the large number of microcracks formed during the grinding process with the A1₂O₃, the fatigue life of parts ground with an A1₂O₃ wheel would be shorter than those ground with CBN. Practical experience indicates that this is true.     

CBN的发展概况及国产CBN硬质合金复合刀片的切削性能试验

简述了美、苏、日、英等工业发达国家CBN的发展现状,并通过三种国产CBN硬质合金刀片的切削试验表明,国产复合刀片既可切淬硬钢,也可切非淬硬钢。CBN的含量、掺杂物、结合剂、CBN的粒径及合成条件(温度、压力)等的不同,将使其切削性能有很大差异。应开发适合加工不同工件材料的CBN系列产品,以充分发挥CBN复合刀片的切削性能。     

CBN tool wear in hard turning: a survey on research progresses

Direct machining steel parts at a hardened state, known as hard turning, offers a number of potential benefits over traditional grinding in some applications. In addition, hard turning has several unique process characteristics, e.g., segmented chip formation and microstructural alterations at the machined surfaces, fundamentally different from conventional turning. Hard turning is, therefore, of a great interest to both the manufacturing industry and research community. Development of superhard materials such as polycrystalline cubic boron nitride (known as CBN) has been a key to enabling hard turning technology. A significant pool of CBN tool wear studies has been surveyed, in an attempt to achieve better processing and tooling applications, and discussed from the tool wear pattern and mechanism perspectives. Although various tool wear mechanisms, or a combination of several, coexist and dominate in CBN turning of hardened steels, it has been suggested that abrasion, adhesion (possibly complicated by tribochemical interactions), and diffusion may primarily govern the CBN tool wear in hard turning. Further, wear rate modeling including one approach developed in a recent study, on both crater and flank wear, is discussed as well. In conclusion, a summary of the CBN tool wear survey and the future work are outlined.     

Ultra-precision grinding of hard steels

Hardened bearing steel, M50, has been ultra-precision ground to produce an optical quality surface (<10 nm R_a) using a novel ultra-stiff machine tool, Tetraform ‘C’. It has been shown that a repeatable surface finish of <10 nm R_a can be produced using a 76 μm CBN grit and 500 μm wheel depth of cut. This represents a significant improvement over previous published work using conventional precision machine tools where nanometre surface finish can only be obtained at the expense of process efficiency.

The development of optical quality surfaces is considered in terms of the processes occurring in the primary and secondary finishing zones of the cup-wheel, with the final surface finish enhanced by the burnishing action of worn CBN grits. It is shown that surface finish is limited by the pull-out of carbides in the secondary finishing zone. However, this can be overcome by using electrolytic in-process dressing (ELID), which maintains CBN grit protrusion and sharpness. This promotes cutting of the carbides at the ground surface and ensures a high level of surface integrity although the burnishing action of grits is reduced resulting in a slightly higher roughness for the steel matrix.     

Tool crater wear depth modeling in CBN hard turning

Hard turning has been receiving increased attention because it offers many possible benefits over grinding in machining hardened steel. The wear of cubic boron nitride (CBN) tools, which are commonly used in hard turning, is an important issue that needs to be better understood. For hard turning to be a viable replacement technology, the high cost of CBN cutting tools and the cost of down-time for tool changing must be minimized. In addition to progressive flank wear, microchipping and tool breakage (which lead to early tool failure) are prone to occur under aggressive machining conditions due to significant crater wear and weakening of the cutting edge. The objective of this study is to model the CBN tool crater wear depth (K_T) to guide the design of CBN tool geometry and to optimize cutting parameters in finish hard turning. First, the main wear mechanisms (abrasion, adhesion, and diffusion) in hard turning are discussed and the associated wear volume loss models are developed as functions of cutting temperature, stress, and other process information. Then, the crater wear depth is predicted in terms of tool/work material properties and process information. Finally, the proposed model is experimentally validated in finish turning of hardened 52100 bearing steel using a low CBN content tool. The comparison between model predictions and experimental results shows reasonable agreement, and the results suggest that adhesion is the dominant wear mechanism within the range of conditions that were investigated.     

超硬磨粒CBN砂轮的磨削性能

本研究的目的是评价三种砂轮在磨削高速工具钢时的磨削性能。采用ABWOOD平面磨床,在不同磨削条件下对材料去除率,比磨削能和磨削表面的热损伤进行了实验研究,同时借助专用装置采集了磨削过程中砂轮的动态磨损数据。研究结果表明,超硬磨粒CBN砂轮磨削M2高速钢时磨性能最佳,这种砂轮在硬铁族金属加工领域具有良好的应用前景。     

CBN砂轮超高速磨削条件下加工表面粗糙度的实验研究

在高速超高速磨削工艺实验基础上,分析了砂轮线速度、切削深度、最大未变形切屑厚度等工艺参数对45#钢、40Cr两种材料磨削表面粗糙度的影响,揭示了在高速超高速磨削条件下用CBN砂轮进行磨削时,表面粗糙度值随砂轮线速度的提高而减小,随切削深度及最大未变形切屑厚度增加而加大的变化规律和机理。为特定材料在高速超高速磨削条件下的加工提供了参考依据。