ELID磨削试验电解参数对光学玻璃表面质量的影响研究

随着国防尖端技术的迅速发展,许多具有独特性能的新材料得到了日益广泛的应用,如光学玻璃、硬质合金.但采用传统磨削工艺加工这些材料很难得到良好的表面质量.在线电解砂轮修整(ELID)磨削技术是一项新的、高效的磨削方法,它有效实现了许多难加工材料的超精密加工和高效加工.针对光学玻璃的特性,将ELID磨削方法应用于光学玻璃的精密加工,通过试验研究ELID磨削中电解参数对加工表面的影响规律,找到了在一定条件下优化的电解参数.试验结果表明,在ELID中,工艺参数对磨削质量及磨削效率有着显著影响,优化工艺参数对ELID镜面磨削有着重要的意义.     

GCr15钢的ELID磨削性能实验研究

为了探讨GCr15钢的ELID（Electrolytic In-process Dressing）磨削性能，在基于大量实验的基础上，对GCr15钢采用ELID磨削时磨削力的变化规律进行了详细分析，并将磨削力、磨削表面粗糙度与普通磨削进行了比较。结果表明，采用铸铁结合剂CBN砂轮进行ELID磨削时磨削力几乎不随时间的变化而变化，而采用白刚玉砂轮进行磨削时的磨削力随时间的变化不断增大，在线电解修整使CBN砂轮在磨削过程中始终保持良好的磨削性能，有利于节省砂轮修整时间，提高加工效率。在ELID磨削中，采用微细砂轮进行磨削可以获得很低的表面粗糙度，实现对GCr15钢的超精密镜面磨削。     

应用ELID技术进行微晶玻璃超精密磨削

由于微晶玻璃具有优良的物理、机械性能，在光学等领域得到了越来越多的应用。ELID磨削利用在线．电解的方法修整超细粒度的金刚石砂轮，可以有效地实现硬脆材料的超精密加工。本文将ELID磨削技术应用于微晶玻璃的超精密加工，通过改进ELID磨削的关键技术，包括砂轮电火花整形、电解修整电源和ELID磨削液的改进，实现了微晶玻璃的超精密磨削加工，同时通过采用原子力显微镜对不同磨削参数下的工件表面进行分析，以保证在塑性状态下对微晶玻璃进行磨削。因此提高了ELID磨削的质量。获得了Ra2．308nm的较好表面质量。     

氧化铝陶瓷ELID高效磨削技术的研究

陶瓷材料具有优异的机械性能，其应用越来越广泛。然而由于陶瓷的高硬度及其易碎性使其难于加工。在线电解修整磨削技术已经被应用于硬脆材料的超精密加工，由于可以实现砂轮的在线修整，尤其被广泛应用于细粒度砂轮的磨削中。本文在平面磨床上应用铸铁结合剂金刚石砂轮与ELID磨削技术进行高效磨削研究。实验结果表明，在同样的磨削条件下，采用ELID磨削时的磨削力约为使用树脂结合剂砂轮磨削力的2／5～3／5。实验结果说明采用ELID磨削技术加工效率可以得到极大提高。而且，在线电解修整作用可以保持砂轮的锋锐性，有利于保持硬脆材料高效磨削的连续性。     

在线电解修整(ELID)超精密磨削中的金刚石磨具特性研究

ELID(Electrolytic In-process Dressing)磨削技术是在电化学加工、电解磨削原理基础上发展起来的一项磨削新技术,主要用于硬脆材料超精密磨削过程中金属基结合剂超硬微细磨粒砂轮的在线修整.本文以金刚石微粉砂轮在线电解修整(ELID)磨削氮化硅陶瓷为例,着重研究了磨具特性对硬脆材料超精密磨削过程的影响.研究表明,磨具组织沿砂轮圆周的不均匀性将会导致砂轮表面钝化膜状态的不一致,这将直接影响砂轮局部参与切削的磨粒数量,影响单个磨料的实际磨削厚度.这首先将对工件表面的磨削质量,特别是对表面粗糙度产生直接影响,同时也非常不利于实现材料的高效去除.     

The effect of ELID grinding on the flexural strength of silicon nitride

Advanced structural ceramics, such as silicon nitride-based materials, are of significant interest due to their excellent physical and mechanical properties. However the cost of grinding these ceramics, an integral part of their fabrication, is very high and can result in surface and subsurface damage to the material. These defects can significantly reduce the strength and reliability of the finished component and are sensitive to grinding parameters. In this investigation, the effect of finish electrolytic in-process dressing (ELID) grinding on the flexural strength of silicon nitride specimens were studied. Kyocera's silicon nitride SN 235, in the form of Modulus of Rupture (MOR) specimens, were ground using the application of ELID grinding with a # 6000 grit sized cast iron bonded diamond (CIB-D) grinding wheel. A significant improvement in the strength of the Si₃N₄ specimens was noted when finish ELID grinding was performed. This was the result of ductile regime grinding using the application of finish ELID grinding. Another method to improve the flexural strength of silicon nitride specimens will also be addressed in this paper.     

ELID grinding and tribological characteristics of TiAlN film

This paper presents the results of electrolytic in-process dressing (ELID) grinding experiments performed on TiAlN film and characterization of the tribological characteristics of the produced films. In advanced films coated by physical vapor deposition, such as CrN and TiAlN, the low surface roughness required for attaining superior tribological characteristics is difficult to attain by use of only a coating process. ELID of grinding wheels improves wheel performance, enabling the attainment of specular finishes on brittle materials, with surface roughness on the nanometer scale (4 to 6 nm). In the present study, high-quality TiAlN film surfaces were fabricated by the ELID technique, typically achieving a surface roughness of around Ra 0.0024 μm by employment of a SD#30,000 wheel. Scanning electron microscopy reveals that ELID improved the finish, as indicated by the shape of grinding marks. Chemical element analysis by an energy-dispersed x-ray diffraction system suggests that ELID grinding formed an oxide layer in the machined surface of TiAlN film. Therefore, in addition to the highly smooth surface, an oxide layer formed by ELID grinding imparts superior tribological properties to ELID-ground TiAlN film.     

Surface finishing of Ni–Cr–B–Si composite coatings by precision grinding

A Ni–Cr–B–Si/10vol%WC coating material has been precision ground to an optical quality surface finish (<10 nm R_a) using a combination of a very stiff precision machine tool, Tetraform “C”, 76 μm CBN grinding wheels and electrolytic in-process dressing (ELID) assisted grinding. When grinding without ELID, surface finish has been shown to be limited by damage to primary and secondary carbides. This damage may be in the form of carbide pull-out or localised fracture and removal of the larger primary WC particulate. ELID assisted grinding helps maintain CBN grit protrusion and sharpness and thus promotes efficient cutting during grinding, minimising pull-out and localised damage to the harder phases within the coating microstructure. ELID therefore improves both the overall surface finish and surface integrity of the workpiece.     

ELID grinding of silicon wafers: A literature review

Silicon wafers are the most widely used substrates for fabricating integrated circuits. There have been continuous demands for higher quality silicon wafers with lower prices, and it becomes more and more difficult to meet these demands using current manufacturing processes. In recent years, research has been done on electrolytic in-process dressing (ELID) grinding of silicon wafers to explore its potential to become a viable manufacturing process. This paper reviews the literature on ELID grinding, covering its set-ups, wheel dressing mechanism, and experimental results. It also discusses the technical barriers that have to be overcome before ELID grinding can be used in manufacturing.     

Development of an on-machine profile measurement system in ELID grinding for machining aspheric surface with software compensation

Efficient manufacture of dimensionally accurate optical surface on hard and brittle materials is a major concern for optoelectronic industry. Electrolytic in process dressing (ELID) grinding is proved as a reliable process to achieve this optical quality nano-surface finish on hard and brittle materials. Besides surface finish it is important to ensure dimensional accuracy by improving profile and form accuracy of the ground aspheric surface. Kinematic factors are commonly considered the reasons for the dimensional inaccuracy in a machined part. Software compensation is a direct and economical method to overcome several kinematic factors and improve the dimensional accuracy. Last, but most important, is the monitoring of achieved surface profile to ensure more accurate profile radius in the finished part. So an on-machine profile measurement system based on coordinate measuring machine (CMM) principle has been developed to check the profile radius of the ground surface. In this study software compensation was applied in ELID grinding of an aspheric surface in order to compensate the wheel wear until the measured surface profile machined on BK7 glass reaches within tolerable limit.     

A study on ELID ultra precision grinding of optical glass with acoustic emission

ELID grinding of BK7 glass and Zerodur was investigated using acoustic emission. Experiments showed that the contacting area between the wheel and workpiece in a grinding process was critical to influence wheel loading for a fine grit size resin-bonded cup wheel. ELID can be used for efficient material removal when the wheel/workpiece contacting area is large. Correlations were observed between the dressing intensity on the ELID wheel and the detected AE signals. Aggressive ELID dressing parameters for grinding with finer grit size wheels corresponded to a lower AE level. With an increase in the processing time of an ELID wheel, low and stable AE amplitudes became large with fluctuations due to the deterioration of the grinding wheel. Results indicate that the AE sensing technique has the potential to be adopted as an effective method for monitoring an ultra precision grinding process, identifying the condition of the grinding wheel and investigating the mechanism of ELID grinding.     

A study on the mirror-like grinding of die steel with optimum in-process electrolytic dressing

In recent years, grinding techniques for the precision machining of brittle materials used in die, mold and optical parts have been improved by using super-abrasive wheels and precision grinding machines. The completion of the optimum dressing of a super-abrasive wheel makes possible the effective precision grinding of die steel STD-11. However, the present dressing system cannot have control of the optimum dressing of the super-abrasive wheel.In this study, a new system and the grinding mechanism of optimum in-process electrolytic dressing are proposed. This system can carry out the optimum in-process dressing of a super-abrasive wheel. Therefore, optimum in-process electrolytic dressing is a good method to for obtaining the efficient and mirror-like grinding of STD-11.     

ELID grinding characteristics of glass-ceramic materials

Zerodur glass-ceramic materials have been widely used in optical, opto-electronic and precision engineering industries; their efficient ultraprecision machining, with extremely low surface roughness and high form accuracy, is in great demand in those fields. The authors have been conducting studies on realizing high-quality surface and form accuracy of zerodur glass-ceramic materials efficiently by use of electrolytic in-process dressing (ELID) grinding process. This paper proposes a new grinding mode in which top surface and sides of zerodur block were ground by cylindrical surface and side surface of grinding wheel. Grinding experiments were carried out using #1200, #2000 and #4000 diamond cast-iron bond wheels, and grinding characteristics such as grinding performance, ground surface roughness, surface topographies and perpendicularity between ground surfaces were investigated. Experiments on grinding using #4000 wheel successfully produced smooth top surface and side surfaces that were about 10 nmRa in surface roughness, 1.5 μm/□400×400 mm² in flatness and 90°±6″ in perpendicularity. AFM observation of the ground surface also showed that material removal in the ductile mode occurs for fine abrasive wheels. The results showed that grinding was stable without severe clogging for wheels by choosing suitable ELID parameters and grinding conditions.     

Depth-of-cut errors in ELID surface grinding of zirconia-based ceramics

Based on the analysis of a surface grinding system and the material removal mechanism, a mathematic model has been proposed to predict the accumulated error between the total set depth-of-cut (DoC) and the total actual depth-of-cut (ADoC) in multi-pass surface grinding of zirconia-based ceramic materials. Design of Experiments (DoE) approach has been implemented to carry out experiments. The influence of the set DoC of each grinding pass, the total set DoC, and the grinding wheel velocity on the accumulated errors in ADoC has been investigated in detail in surface grinding of zirconia-based ceramics both with electrolysis in-process dressing (ELID) and without ELID. It has been observed that the accumulated DoC errors increase faster in the first few passes and gradually reach a saturation after a certain total DoCs (about 8–10 grinding passes) and a higher step DoC leads to a faster (fewer passes) saturation of the accumulated DoC errors. Compared to grinding without ELID, it has been found that ELID-grinding is characterized with better process stability and ELID offers positive effects on material removal rate (MRR), especially in case of removing large volume of material with the same grinding parameters.     

以工件材料作为修整电极的球面ELID精密磨削试验研究

针对小球面硬质合金精密磨削的技术难题,尝试对硬质合金做ELID(Electrolytic In-process Dressing)成形范成法凹球面磨削试验。因为被加工凹球面直径小,受空间限制无法解决修整电极的安装问题,又由于硬质合金工件自身导电性良好,因此采用以工件做电极的ELID磨削试验方案。考虑到磨削过程中的火花放电现象对磨削表面质量的负面影响,设计"间歇电解修锐ELID磨削"(简称ELID-Ⅱ)和"连续电解修锐ELID磨削"(简称ELID-Ⅲ)两种方案进行试验。初步试验结果为:"ELID-Ⅱ"磨削后表面粗糙度值为Ra0.12μm和球面度误差6.99μm,"ELID-Ⅲ"获得表面粗糙度值为Ra0.53μm和球面度误差57.76μm,"ELID-Ⅱ"优于"ELID-Ⅲ"。     

二维超声ELID复合平面磨削系统磨削力研究

对硬脆材料在二维超声电解在线砂轮修整技术（electrolytic in-process dressing,ELID）复合平面磨削条件下的磨削力进行理论研究,建立超声ELID复合磨削力模型。由磨削力公式可知:磨削力除了与超声波的振幅、角频率有关外,同时还受到电流的影响,且随电流的减小,磨削力逐渐增大。在不同磨削深度与砂轮转速条件下采集磨削力,并与理论值进行对比。结果显示:理论值与实测值趋于一致;法向磨削力与切向磨削力均随着磨削深度的增大而增大,随着砂轮转速的增大而减小。      

超硬磨料砂轮修整与ELID修磨技术

超硬磨料砂轮由于其优良的磨削性能，广泛应用于航空、汽车、医学、电子、建材等领域，并成为精密和超精密磨削、高速高效磨削、难加工材料磨削、成形磨削、磨削自动化等技术的基础。本文简要概述了近年来超硬磨料砂轮修整的一些新方法与ELID修磨技术。     

Precision surface grinding of Mn–Zn ferrite with in-process electro-discharge dressing (IEDD)

Ferrite is widely used as a material for hard disk magnetic heads, but is difficult to grind because of its high hardness and brittleness. Therefore, a superabrasive (diamond) wheel is used for precision surface grinding of this material. But the conventional dressing method cannot be applied to the diamond wheel. This study describes a newly proposed method for carrying out effective in-process electro-discharge dressing (IEDD) of a diamond wheel. Using IEDD, the surface roughness of Mn–Zn ferrite was improved and the grinding force was reduced. IEDD is a good method to obtain efficient grinding and surface grinding of ferrite.     

冷轧钢渗碳处理后的ELID磨削效果及加工表面硬度实验研究

本文采用在线电解修整磨削技术,对经渗碳处理后的冷轧钢进行超精密镜面磨削试验,获得表面粗糙度达Ra6～8 nm的加工表面.实验结果表明:采用微细粒度、高硬度铸铁基金刚石砂轮、提高砂轮线速度和减小磨削深度可有效地提高表面质量,降低表面粗糙度;磨削过程中,砂轮线速度、磨削深度、磨削液是影响加工表面质量的主要因素.     

Mirror surface grinding for brittle materials with in-process electrolytic dressing

Use of a diamond wheel with superabrasive is required for mirror-like surface grinding of brittle materials. However, conventional dressing methods cannot apply to the diamond wheel with superabrasive. Recently, an electrolytic dressing method was developed for use with a cast iron-bonded diamond wheel and superabrasive. This technique can replace lapping and polishing. Using electrolytic dressing, surface roughness of the workpiece was improved significantly, and the grinding force was very low and the continuity of the grinding force was also improved. The purpose of this study was to achieve mirror-like surface grinding of ferrite with electrolytic dressing of a metal-bonded diamond wheel. For application of ultraprecision grinding for brittle material, superabrasive, air spindle, and in-process electrolytic dressings were used. Additionally, the effects of pick current and pulse width on ground surface were investigated, and suitable dressing conditions for ferrite were determined.