结合ELID磨削与磁流变光整加工的单晶硅反射镜超精密制造技术

分析了在线电解修整（ELID）磨削和磁流变光整加工（MRF）的加工原理与特点，充分结合这2种技术的优点对单晶硅反射镜进行纳米级精度的组合加工．首先进行ELID高效率磨削，在线检测工件表面误差后进行补偿磨削，使反射镜面加工成形，并获得较好的形状精度和表面质量．然后，利用磁流变技术进行确定性的光整加工，以减少反射镜的亚表面损伤，使加工表面的形状精度与表面粗糙度得到很大提高与改善．利用该组合工艺，对硅反射镜进行了系列的加工实验，高效率地得到了低于1nmRMS的表面粗糙度和69nmp-V形状精度的工件表面．     

ELID磨削砂轮表面氧化膜力学性能

砂轮表面的氧化膜对保证在线电解修整（ELID）磨削的非线性电解以及对改善磨削表面质量都具有极其重要的作用.利用纳米压痕技术研究了氧化膜的硬度、弹性模量及刚度.研究结果表明,氧化膜的硬度约为210MPa,是基体硬度的1/4-1/3,使氧化膜有效地隔离了基体与工件,避免基体划伤磨削表面;氧化膜弹性模量约为30-50 GPa,是基体弹性模量的1/6-1/3,因此弹性变形更易发生,有利于磨粒的协同性与等高性;氧化膜刚度约为15μN/nm,由于氧化膜的动态更新,其值与磨削参数有关.在精密磨削时,由于氧化膜发生弹性变形,减小了磨粒的出刃高度和磨削深度,使磨削表面质量得到改善.     

反应烧结碳化硅磨削参数优化及机理研究

针对反应烧结碳化硅（RB-SiC）的磨削工艺参数及其磨削机理进行研究。着重分析了磨削工艺参数对反应烧结碳化硅材料的表面粗糙度Ra、磨削效率和显微硬度以及磨削后陶瓷表面形貌的影响并确定最佳磨削工艺参数。最佳磨削条件为磨削深度0．47μm／s、工作台速度2．5r／min和光磨时间5min。磨削后碳化硅Ra最低（Ra〈100nm），加工硬化变质层较小，表面完整性较好。同时对反应烧结碳化硅的磨削机理进行研究，确定其是以脆性断裂为主的材料去除方式，其形式包括晶粒去除、材料剥落、脆性断裂等。     

不同晶粒度硬质合金的磨削力预测

介绍了磨削力数学模型研究现状,在断裂力学基础上建立了与工艺参数和材料物理机械性能相关的磨削力数学模型,可根据数学模型预报不同晶粒度硬质合金的磨削力为了论证此磨削力数学模型,对不同晶粒度的硬质合金进行了磨削实验．分析了晶粒度和工艺参数对磨削力、磨削表面形貌的影响,讨论了硬质合金物理机械性能对磨削力的影响．实验研究结果表明,数学模型预估值与实验数据吻合程度高,晶粒度对磨削力和磨削表面形貌都有显著影响．在相同磨削条件下,减少硬质合金晶粒度则磨削力减少,并且磨削表面质量改善,反之亦然．细磨粒砂轮磨削时晶粒度对磨削力的影响程度减弱．     

整体硬质合金刀具表面缺陷非破坏检测方法

针对整体硬质合金刀具磨削裂纹等表面缺陷的无损检测,重点分析和讨论了后乳化型荧光渗透探伤法及其在整体硬质合金刀具质量保障技术领域中的应用情况,并确定了刀具的荧光渗透检测工艺流程和工艺参数。最后对整体硬质合金刀具磨削裂纹等表面缺陷的形态分布规律进行了归纳和分析。     

粗晶TM52钢结硬质合金的冲击磨料磨损性能研究

系统对比研究了粗晶粒TM52钢结硬质合金与分别采用真空烧结和低压烧结制备的细晶粒TM52钢结硬质合金在不同冲击功工况下的抗磨料磨损性能与行为,并在对磨损面形貌进行电镜观察分析的基础上探讨了粗晶粒TM52钢结硬质合金的磨损机理。研究发现,粗晶TM52合金的抗磨料磨损性能随着冲击功的逐步提高呈现先下降后增强的变化规律,这与其高锰钢基体在高冲击功条件下的高硬化速率及硬化效果更快、更充分有关。相对于细晶粒钢结硬质合金,粗晶粒TM52钢结硬质合金在抗冲击磨料磨损方面具有明显的性能优势,尤其在高冲击功(3~4J/cm~2)条件下,耐磨性能可提高40%~80%。在此工况下磨损机制主要为碾碎性磨料磨损、擦伤式磨料磨损和疲劳磨损,凿削式磨料磨损不明显。     

增强相对铝基复合材料超精密加工表面的影响

采用聚晶金刚石（PCD）刀具对SiC增强铝基复合材料进行超精密车削加工试验,基于原子力显微镜（AFM）、扫描电子显微镜（SEM）和Talysurf-6型轮廓仪对加工表面进行检测和分析.结果表明,S iC增强相的切削变形机理对超精密级加工表面的影响重大（粗糙度Ra为0.025μm）.若增强相在解理面直接被切削刀具切断,则SiC增强相附近区域的表面粗糙度值范围为6~10 nm,故产生超精密级加工表面的可能性大;若增强相以拔出或压入的机理进行切削变形,则不易获得超精密级加工表面.较高的切削速度、较小的进给量、较小的刀具钝圆半径和较大的PCD刀具晶粒度都有助于获得超精密级的加工表面,而背吃刀量对其影响很小.SiC增强相的体积分数和类型也是影响超精密级表面质量的重要因素,增强相体积分数越高,表面质量越差,晶须增强铝基复合材料较颗粒增强铝基复合材料可获得更好的表面质量.     

反应烧结碳化硅磨削参数优化及机理研究

针对反应烧结碳化硅(RB-SiC)的磨削工艺参数及其磨削机理进行研究.着重分析了磨削工艺参数对反应烧结碳化硅材料的表面粗糙度Ra、磨削效率和显微硬度以及磨削后陶瓷表面形貌的影响并确定最佳磨削工艺参数.最佳磨削条件为磨削深度0.47μm/s、工作台速度2.5 r/min和光磨时间5min.磨削后碳化硅Ra最低(Ra＜100 nm),加工硬化变质层较小,表面完整性较好.同时对反应烧结碳化硅的磨削机理进行研究,确定其是以脆性断裂为主的材料去除方式,其形式包括晶粒去除、材料剥落、脆性断裂等.     

结构陶瓷磨削表面微裂纹的研究

结构陶瓷的磨削表面微裂纹是较常见和较危险的磨削损伤，本文应用压痕断裂力学。磨削表面热应务陶瓷微观结构的有关知识分析了结构陶瓷表面裂纹的形成机理、形状特征及奖表面的延伸，并对几种典型结构民磨削表面层的微观状态进行了大量的ＳＥＭ观察，结果表明：（１）磨削微裂纹与陶瓷的断裂韧性Ｋ１Ｃ和显微硬度Ｈ之比、陶瓷的热特性及磨削工艺参数有关；（２）磨削微裂纹的 压痕效应径向裂纹、热裂纹、（３）细晶陶瓷多为穿晶裂纹     

TiC钢结硬质合金的研究进展

介绍了TiC钢结硬质合金的性能特点和设计原则.比较系统地综述了TiC钢结硬质合金各种不同的制备方法,讨论并比较了它们的工艺特点,其中重点考察了原位合成技术在制备TiC钢结硬质合金中的应用,展望了TiC钢结硬质合金的发展前景.     

Highly Efficient and Precision Fabrication of Cylindrical Parts from Hard Materials with the Application of ELID (Electrolytic In-Process Dressing)

The ELID (Electrolytic In-Process Dressing) grinding process, which incorporates in-process dressing of metal bonded superabrasive wheels, was applied for efficient and precision grinding of hard materials such as ceramic, hard metals, and quenched steels. Addressed in this paper are some of the typical applications of ELID Grinding for cylindrical machining. The significant advantages, performances, and characteristics of mirror surface grinding for external surface, internal surface, and end-face Finish processes of cylindrical components are described.     

Ductile Regime Mirror Finish Grinding of Ceramics with Electrolytic In-process Dressing (ELED) Grinding

Advanced structural ceramics, such as silicon nitride based materials, are of interest owing to their unique physical and mechanical properties. However the cost of grinding these ceramics, which is an integral part of their fabrication, is very high. Moreover, grinding can result in surface and sub-surface damage in the material and these defects can significantly reduce the strength and reliability of the finished components. Grinding damage is sensitive to grinding parameters. Two types of silicon nitride based ceramic materials were ground with Electrolytic In-Process Dressing (ELID) using different grit sized metal bonded diamond grinding wheels. With the application of ELID technology, mirror surface finish was realized with a #4000 mesh size wheel (average grain size = 4μm). Differences in ground surface topography caused by wheel grain size were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM and AFM studies reveal that material was predominantly removed in the ductile mode when ELID grinding was performed with a #4000 grit size wheel or finer.     

Highly Efficient Grinding of Ceramic Parts by Electrolytic In-Process Dressing (ELID) Grinding

In the manfacture of structural ceramic components, it has been well documented that the grinding costs can be as high as 90% of the total cost. Grinding costs of ceramics can be reduced by maximizing the material removal rates (MRR). A novel grinding technology that incorporates in-process dressing of metal bonded superabrasive wheels, known as Electrolytic In-Process Dressing (ELID) has been developed (1) which can significantly increase the MRR. This technique uses a metal bonded grinding wheel that is electrolytically dressed, during the grinding process, for continuous protrudent abrasive from superabrasi ve wheels. The principle of ELID grinding technology will be discussed in this paper as will its application for rough grinding. The effects of various parameters such as wheel bond type and type of power supply on the ELID grinding mechanism will also be addressed in this paper.     

Precision grinding of microarray lens molding die with 4-axes controlled microwheel

This paper deals with precision grinding of microarray lens (fly eye) molding die by using a resinoid bonded diamond wheel. An ultra-precision grinding system of microarray lens molding die and new truing method of resinoid bonded diamond wheel were developed. In this system, a grinding wheel was four-dimensionally controlled with 1 nm resolution by linear scale feedback system and scanned on the workpiece surface. New truing method by using a vanadium alloy tool was developed and its performance was obtained with high preciseness and low wheel wear. Finally, the microarray lens molding dies of fine grain tungsten carbide (WC) was tested with the resinoid bonded diamond wheel to evaluate grinding performance.     

Grinding Characteristics of Hard and Brittle Materials by ELID-Lap Grinding Using Fine Grain Wheels

In this investigation, ceramics such as zirconia and silicon carbide were ground by lap grinding using the ELID (electrolytic in-process dressing) method and using various-sized metal bonded wheels (mesh sizes of #1200-#8000). Differences in the ground finish, according to the wheel grain size, and surface roughness were investigated through the use of a Scanning Electron Microscope (SEM). It was found that the ground surface roughness improved proportionally to the grain size. The SEM observations also showed that the ground surfaces using wheels over #4000 were very smooth with several minute ground grooves crossing each other without brittle fracture. Brittle-ductile transition was studied using these wheels and the removal mechanisms of silicon and tungsten carbides were also investigated. It was found that for silicon, brittle-ductile transition was obtained using wheels over #8000 and for tungsten carbides, transition was achieved using wheels over #4000. Therefore, the work materials affect the changes in the removal mechanism.     

Nano finish grinding of brittle materials using electrolytic in-process dressing (ELID) technique

Recent developments in grinding have opened up new avenues for finishing of hard and brittle materials with nano-surface finish, high tolerance and accuracy. Grinding with superabrasive wheels is an excellent way to produce ultraprecision surface finish. However, superabrasive diamond grits need higher bonding strength while grinding, which metal-bonded grinding wheels can offer. Truing and dressing of the wheels are major problems and they tend to glaze because of wheel loading. When grinding with superabrasive wheels, wheel loading can be avoided by dressing periodically to obtain continuous grinding. Electrolytic inprocess dressing (ELID) is the most suitable process for dressing metal-bonded grinding wheels during the grinding process. Nano-surface finish can be achieved only when chip removal is done at the atomic level. Recent developments of ductile mode machining of hard and brittle materials show that plastically deformed chip removal minimizes the subsurface damage of the workpiece. When chip deformation takes place in the ductile regime, a defect-free nano-surface is possible and it completely eliminates the polishing process. ELID is one of the processes used for atomic level metal removal and nano-surface finish. However, no proper and detailed studies have been carried out to clarify the fundamental characteristics for making this process a robust one. Consequently, an attempt has been made in this study to understand the fundamental characteristics of ELID grinding and their influence on surface finish.     

Grinding of Toroidal and Cylindrical Surfaces on SiC Using Diamond Grinding Wheels

This paper presents the methods and experimental results for grinding toroidal and cylindrical surfaces made of silicon carbide using diamond grinding wheels and an inexpensive CNC machining center. The mirrors were successfully obtained by automatic grinding operations with good shape accuracy, mirror surface finish, and low roughness heights. The time consumed in the process is very short. Industrial manufacture of lenses usually involves three operations — grinding without dressing, lapping, and polishing. In the laboratory studies, however, mirrors and lenses have been manufactured only with grinding process, because of 100% ductile-mode material removal in grinding with dressing. These processes were individually evaluated for surface roughness and surface integrity using surface roughness testers and a scanning electron microscope.     

CVD‐Diamantschleifstifte für den Werkzeug‐ und Formenbau. Abrasive Pencils for Tool and Die Making Coated by Diamond CVD

Recently developed compeDIA®‐ abrasive pencils have been produced and tested for the machining of cemented carbide molding tools. In order to produce abrasive pencils, carbide base plates have been grinded and coated with a diamond layer by a Hot‐Filament‐CVD‐process. The testing of the abrasive pencils took place with an ultra‐precision grinding machine on carbide workpieces. Surface roughness of the workpiece and its wheel life were the criteria for evaluation. For the specific adjustment of the grain size of the abrasive pencils, the adequate coating parameters were worked out, and the dependencies on basic influencing variables at coating procedures, such as nominal diameter and grinding length, were calculated. In order to be able to coat the grinded base plates with enough film adhesion, a practical pre‐treatment method was developed and tested, which removes the fringe zone, that was damaged during the grinding process. At present, the costs for the coating process are uneconomically high, though. By means of large‐scale production in connection with an automated pre‐treatment and coating it would be possible to lower the costs so far that they are on the same cost level with other coatings like TiN or TiAlN. The CVD‐Diamond abrasive pencils are very appropriate for tool and die making. It is to be expected that through further development of tools and through process optimization, the quality of the wrought workpiece can be ameliorated and surface finishes of R_a < 0,3 μm can be reached. The wheel life could be increased to appropriate values by optimization of the coating technology. The range of the machining parameters, in which the grinding process can be accomplished expediently without leading to a broken die, have been worked out. Afterwards, a die‐casting component with typically shaped elements was designed and an adequate molding tool prototype was crafted. With that, the basic conditions for tool‐ and die‐making were worked out in order to put into practice a fast and flexible machining of cemented carbide molding tools with the aid of those innovative abrasive pencils. In contrast to the traditional molding tool material made of brass, clear advantages in tool life can be made in the production of miniature serial‐parts by drawing, deep‐drawing or extrusion.     

Schleifbearbeitung von Hart‐Weich‐Verbunden – Finite‐Elemente‐Simulation des Schleifprozesses von hybriden Schichtverbunden

Grinding of ceramic‐metal‐compounds – finite element analysis simulation of the grinding process of hybrid stratified compounds In this paper, the subproject TP 8 “Grinding of ceramic‐metal‐compounds” is been introduced. An adapted grinding strategy should be created for the production of a ceramic‐cemented carbide compound drill. This aim should be obtained with experimental analysis and the use of finite element analysis to simulate the grinding process of ceramic‐cemented carbide compound drill. Furthermore a basic approach for simulating the grinding process of hybrid stratified compounds is been presented, which should be a basis for a finite element analysis simulation of a grinding process of ceramic‐cemented carbide compound drill.