氧化铝陶瓷缓进给磨削机理的研究

本文通过扫描电子显微镜对氧化铝陶瓷缓进给磨削后的表面进行详尽的观察，对氧化铝陶瓷的磨削机理进行研究。研究表明对氧化铝陶瓷进行缓进给磨削时，主要以脆性崩碎方式去除材料，并伴随着一定量的塑性流动，给出了氧化铝陶瓷在缓进给磨削方式下无裂纹磨削方法。同时研究了磨削参数对表面粗糙度的影响，实践证明工程陶瓷材料以缓进给方式磨削和特定的磨粒粒度下表面粗糙度Ra值是稳定的。     

应用电泳技术塑性磨削硅材料的研究

半导体、光学玻璃及工程陶瓷等硬脆性材料因其独特的物理、机械性能 ,已成为尖端科学技术中应用最活跃的先进材料。世界许多国家在投入大量人力物力开发具有特殊价值的新型硬脆性材料的同时 ,对这些材料的加工技术进行了广泛的研究。硬脆性材料的精密、超精密加工 ,普遍采用磨削、研磨等加工技术。在磨削过程中 ,减少磨粒单刃切除量是减少加工表面微观破损、提高加工精度的发展方向。本文结合塑性方式磨削技术和电泳磨削技术 ,对半导体硅材料进行塑性方式磨削试验研究。一、塑性磨削技术材料的去除机理一般分为脆性和塑性。硬脆性材料的特点…     

石英玻璃的热辅助高效塑性域干磨削

为了提高大口径石英玻璃光学元件的加工效率,提出了热辅助塑性域超精密磨削石英玻璃的新方法。分析了石英玻璃的热辅助塑性域磨削机理,通过理论推导得出磨削深度对磨削区表面最高温升的影响规律。采用陶瓷结合剂立方氮化硼(CBN)砂轮对石英玻璃进行干磨削,利用磨削热改善磨削区石英玻璃的力学性能,实现了石英玻璃的高效塑性域磨削。通过磨削实验研究了不同磨削深度对石英玻璃表面粗糙度(Ra)和亚表面损伤深度的影响。实验结果表明,随着磨削深度的增加,Ra和亚表面损伤深度反而降低。当磨削深度为5μm,大于粗磨表面的裂纹深度时,获得了Ra值为0.07μm的光滑无裂纹的塑性域磨削表面。通过扫描电镜观察研究了砂轮的磨损机理,结果显示陶瓷结合剂CBN砂轮塑性域干磨削石英玻璃时,砂轮以磨耗磨损为主,该结果为研究新型的陶瓷结合剂CBN砂轮提供了依据。     

部分稳定氧化锆PSZ高效深磨磨削力试验研究

本文对部分发稳定氧化锆陶瓷（Panialy stabilized Zirconia，PSZ）在高效深磨条件下的磨削力进行了试验研究，分析了各种因素对磨削力的影响，并与其它磨削方式的PSZ陶瓷作了比较和综合分析。分析表明：PSZ陶瓷在高效深磨条件下，当比材料去除率一定时，工作台速度的变化对磨削力的影响比切深的变化对磨削力的影响大；磨削力与普通磨削相比较大，比材料去除率是普通磨削的几十倍；材料去除模式以显微塑性去除为主，磨削工件表面质量较好。     

钛基复合材料高速磨削加工磨削力仿真分析

为了探究颗粒增强钛基复合材料磨削过程中的磨削力,建立了PTMCs磨削仿真模型对PTMCs磨削力进行仿真分析,通过磨削试验验证了模型的准确性。结果表明,在磨削过程中,PTMCs的基体以锯齿状切屑方式塑性去除,去除过程中磨削力呈现规律性的波动; PTMCs的颗粒增强相以块状切屑方式脆性去除,去除过程中磨削力呈现很大幅度的波动。此外研究表明,法向磨削力和切向磨削力随着单颗切厚和切削速度的增大均增大。     

磨削技术的现状和未来发展趋势

介绍了实现超高速磨削的理论依据,概述了近年来国内外磨削技术的研究现状和发展趋势,阐述了超高速磨削机理、优越性及其特点,列举了实现超高速磨削技术的若干关键技术。高速和超高速磨削是提高磨削效率、降低工件表面粗糙度和提高零件加工品质的先进加工技术。超高速磨削能够越过磨削过程的高温死谷,避免工件表面磨削烧伤,可以实现对硬脆材料的延性域磨削以及对高塑性、难磨材料也有良好的磨削表现。     

二维超声磨削纳米氧化锆陶瓷的磨削力特性研究

对纳米氧化锆陶瓷在二维超声磨削条件下的磨削力进行了理论分析与实验研究,并与相同磨削参数下的普通磨削方式的磨削力进行了比较和分析。研究表明:与普通磨削相比,二维超声磨削可获得椭螺线式的加工轨迹,大大减小了平均磨削力,扩大了纳米陶瓷的塑性加工域,表面质量得到明显的改善。     

单晶硅片磨削的表面相变

为揭示硅片自旋转磨削加工过程中材料的去除机理,采用显微拉曼光谱仪研究了硅片磨削表面的相变.结果表明:半精磨和精磨硅片表面存在α-Si相、Si-Ⅲ相、Si-Ⅳ相和Si-Ⅻ相,这表明磨削过程中Si-Ⅰ相发生了高压金属相变(Si-Ⅱ相).Si-Ⅱ相容易以塑性方式去除.粗磨硅片表面没有明显的多晶硅,只有少量的非晶硅出现,材料以脆性断裂方式去除.从粗磨到精磨,材料去除方式由脆性断裂去除向塑性去除过渡.粗磨向半精磨过渡时,相变强度越大,材料的塑性去除程度越大;半精磨向精磨过渡时,相变强度越小,材料的塑性去除程度越大.     

单晶硅片磨削表面相变研究

为了揭示硅片自旋转磨削加工过程中材料的去除机理,采用显微拉曼光谱仪研究了硅片磨削表面的相变。结果表明：半精磨和精磨硅片表面存在-Si相、Si-III相、Si-IV相和Si-XII相,这表明磨削过程中Si-I相发生了高压金属相变（Si-II相）,Si-II相容易以塑性方式去除。粗磨硅片表面没有明显的多晶硅,只有少量的非晶硅出现,材料以脆性断裂方式去除。从粗磨到精磨,材料去除方式由脆性断裂去除向塑性去除过渡。粗磨向半精磨过渡时,相变强度越大,材料的塑性去除程度越大;半精磨向精磨过渡时,相变强度越小,材料的塑性去除程度越大。     

缓进给磨削磨削液的加注方式

分析了缓进给磨削磨削液加注方式对冷却效果的影响，并在此基础上，提出了一项射流冲击强化磨削弧区换热的新技术。     

Specific grinding energy as an in-process control variable for ductile-regime grinding

This article addresses the problem of monitoring the material removal regime (ductile versus brittle) that occurs during the grinding of brittle materials. Often a ductile grinding regime is desired, but currently there is no way to measure the grinding ductility “in process.” A model is developed to describe the dependence of the specific grinding energy on the material removal regime. It is found that the specific grinding energy will remain relatively constant for ductile-regime grinding but will decrease in a power-law relationship with an increasing material removal rate for brittle-regime grinding. Experimental confirmation of the proposed model is presented. The potential for using measurements of specific grinding energy to control the grinding ductility is established, and the benefits of such a closed-loop feedback system in ductile-regime grinding are explained.     

Acoustic emission as an indicator of material-removal regime in glass micro-machining

Acoustic emission (AE) spectra were recorded during microgrinding of brittle materials. It was found that the specific AE energy (i.e., the measured AE energy divided by the material removal rate) was lower for fracture-dominated grinding than for plastic flow-dominated grinding. Two subsequent experiments were performed to measure AE energy while holding the material-removal rate constant. By controlling either the critical depth of cut (for ductile-brittle transition) of the workpiece material, or the actual depth of cut of the grinding machine, the sensitivity of AE energy to grinding regime was investigated for grinding with a constant material-removal rate. Contrary to conventional thinking about the relative contributions of plastic flow and fracture in generation of AE activity, it was found that the AE energy was larger in ductile-regime grinding than in brittle-regime grinding, for identical material removal rates. As a result of the experiments described in this paper, it can be concluded that AE energy measured during microgrinding is sensitive to changes in the mechanism of material removal. For a given volume of material removed, there is more AE energy in a plastic flow-dominated process than in a fracture-dominated process. The relationship found between AE energy and material removal regime could lead to an in-process sensing strategy for controlling grinding ductility.     

On Material Removal Regimes for the Shaping of Glass Edges: Force Analysis,Surface Topography and Damage Mechanisms

Glass shaping, which corresponds to the removal of the edges of a specimen, is the last finishing operation in glass manufacturing. This process has several functions on the final shaped glass including removing sharp edges, improving mechanical resistance, decreasing surface damage and giving it an aesthetical aspect. This article addresses the effects of working parameters, including grinding forces and consumed power, on surface edge finishing and damage mechanism induced during glass grinding. Microscopic observations and multi-scale analysis have also been conducted to investigate the surface edge characteristics. Experimental results show three damage regimes. The first (regime I) is a partial ductile regime with cutting action accompanied by chip formation. The second (regime II) is a crushing (or fragmentation) regime. The last (regime III) is also a partial ductile regime but by ploughing action with displaced material. The shaped surface obtained in the regime II has a better roughness than that obtained in regime I and III. However, regimes I and III include streaks and form defects which are not present in regime II. Similar to metallic materials, the evolution of force components show a linear relationship between normal and tangential forces. This implicates a constant average contact pressure and friction coefficient (μ) between the flat grains and the workpiece.     

超高速冲击磨削天然大理石磨削机理研究

使用人造金刚石和立方氮化硼（CBN）磨料，以7．62mm子弹为载体，利用81式步枪作为加速装置，对天然大理石进行了720m／s的超高速冲击磨削实验，并对实验结果进行了分析和检测。通过对冲击区形貌的观察，发现了超高速冲击成屑现象；通过对金刚石和CBN在大理石表面所留下的细微划痕的分析，得出了脆性材料在超高速磨削条件下可以获得延性域磨削效果的结论。     

Micro/nano Indentation and Single Grit Diamond Grinding Mechanism on Ultra Pure Fused Silica

The existing research about ductile grinding of fused silica glass was mainly focused on how to carry out ductile regime material removal for generating very smoothed surface and investigate the machining-induced damage in the grinding in order to reduce or eliminate the subsurface damage.The brittle/ductile transition behavior of optical glass materials and the wear of diamond wheel are the most important factors for ductile grinding of optical glass.In this paper,the critical brittle/ductile depth,the inf...     

Analysis of the grain depth-of-cut in plunge grinding

The grain depth-of-cut in plunge grinding was analyzed using computer simulation and an analytic model. Two regimes were identified for the depth-of-cut as a function of the infeed. At lower infeeds, there is a unique correlation between grinding grooves and cutting grains, and the depth-of-cut is equal to the infeed. At higher infeeds, the correlation is destroyed, and the depth-of-cut can be much less than the infeed. An analytic model that takes into account only the mean surface position while ignoring the surface profile can describe the latter regime.     

An investigation into parallel and cross grinding of BK7 glass

Conventional grinding of BK7 glass will normally result in brittle fracture at the surface, generating severe sub-surface damage and poor surface finish. The precision grinding of BK7 glass in parallel and cross grinding modes has been investigated. Grinding process, maximum chip thickness, ductile/brittle regime, surface roughness and sub-surface damage have been addressed. Special attention has been given to the condition for generating a ductile mode response on the ground surface. A polishing–etching method has been used to obtain the depth of sub-surface damage. Experiments reveal that the level of surface roughness and depth of sub-surface damage vary differently for different grinding modes. This study gives an indication of the strategy to follow to achieve high quality ground surfaces on brittle materials.     

中性腐蚀环境下钢丝的微动疲劳行为

在自制的微动疲劳试验机上开展中性腐蚀环境下单根钢丝的微动疲劳实验,考察在相同接触载荷下,不同振幅对钢丝的微动疲劳行为的影响,并用扫描电子显微镜观察疲劳钢丝的磨痕和断口形貌,研究钢丝微动疲劳断裂机制.结果表明:在较大的振幅下,钢丝的微动区均处于滑移状态,而在较小振幅下,钢丝的微动区从滑移状态逐渐转变为黏着状态;磨损机制主要为磨粒磨损、疲劳磨损、腐蚀磨损和塑性变形;钢丝疲劳寿命随着微动振幅的增大而减小;钢丝的疲劳断口可分为3个区域,即疲劳源区、裂纹扩展区及瞬间断裂区.     

Precision grinding of binderless ultrafine tungsten carbide (WC) microstructured surfaces

The primary objective of this study was to produce binderless ultrafine tungsten carbide (WC) microstructured surfaces in the ductile grinding regime and to optimize machining parameters to generate microstructural features and sharp edges without chipping. The micro-deformation, fracture properties, and grinding mechanisms were characterized using micro/nano-indentation and single-grit grinding experiments. The effects of grinding conditions (such as grinding mode, feed rate, and spindle speed) on ground surface quality and the radius and chipping of edges were investigated using microstructural grinding experiments. It was found that in nano-indentation, the binderless WC indentation was accommodated by plastic deformation. An average critical depth of cut of 146 nm could be achieved on single-grit scratching tests using atomic force microscopic procedures. In grinding of microstructured surfaces, the surface roughness of side surfaces was always smaller than that of the bottom surface of the machined feature. The better surface quality and sharper edges were obtained by using the upcut grinding mode. Reducing the tool feed rate did necessarily help to improve the surface roughness and edges of structures. The best ground surface could be obtained at the grinding speed of 2,500 rpm. According to the grinding experimental results, an echelle grating was manufactured using the optimized parameters. The average surface roughness SRa of the bottom surface was 78 nm and that of the side surface was 60 nm. The radius of the edge was less than 1 μm, and the radius of corner was about 3 μm. No visible evidence of grinding-induced cracks and chipping on the ground surfaces was found.     

Effect of Cold Rolling on the Fretting Wear Behavior and Mechanism in Inconel 690 Alloy

The influence of cold rolling on the fretting wear behavior and mechanism of Inconel 690 alloy at 320?°C in air was studied. The wear volume and worn surface were obtained and analyzed using laser scanning confocal microscopy, electron back-scattering diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The grinding surface and strain distribution were also studied by electron back-scattering diffraction to analyze the mechanism of fretting damage. The results indicated that with an increase in cold rolling reduction, the microhardness was increased. However, the friction coefficient and wear volume first increased and then decreased. The characteristics of fretting areas changed from a gross slip regime to a partial slip regime. Accordingly, the damage mechanism in the gross slip regime was a combination of oxidative wear, abrasive wear, and delamination, whereas the damage mechanism in the partial slip regime was mainly adhesive wear.