3D打印超硬磨粒工具研究与展望

随着加工产业向着高精密方向发展,超硬磨粒工具的应用越来越广泛。传统制造业很难实现对于具有内外部复杂结构、高加工精密度、高度个性化加工工具制造。新兴的增材制造技术又称3D打印,与传统的材料成型技术最大的区别在于它的材料利用率较高,可以以一种快速的由原材料层层累加的方式生产出任意形状的产品,有望击破传统超硬磨粒工具生产壁垒。文章主要介绍了主流适用于制造超硬磨粒工具的3D打印技术,如光固化成型技术、激光烧结技术和三维打印成型技术,阐述了每种技术的工艺原理,同时指出了目前存在的问题,对未来3D打印技术成型超硬磨粒工具进行展望。     

模具自由磨粒精密光整加工技术

论述了自由磨粒精密光整加工方法的原理、特点、关键技术及具体应用，其目的是在模具制造业中，利用自由磨粒进行光整加工，实现低成本、高表面完整性、高效率精密加工。     

光电子材料的磨粒加工技术综述

随着通讯、信息产业的迅速发展,各种光电子元件得到惊人的发展并趋于高性能化,对光电子材料的加工技术也提出了更高的要求.文章从锯切、磨削、抛光三个方面介绍了光电子材料的磨粒加工技术,并对光电子材料磨粒加工技术的发展趋势进行了展望.     

超精陶瓷抛磨粒研究

通过研究成型密度、结合剂用量及结合剂耐火度对超精陶瓷抛磨料性能的影响，探讨出常用陶瓷抛磨粒的配方范围是：结合剂含量为85％－65％，成型密度为2．32－2．45g/cm^3；在1250℃-1300℃的烧成范围内，结合剂的耐火度应为1200℃-1350℃。同时还介绍了适用于陶瓷抛磨粒成型的工艺参数。     

磨粒流加工技术简介

介绍了磨粒流加工技术的原理及磨粒流加工系统的组成;列出了其与传统机械加工方法相比具有的优势,并从加工零件的内部处理和外部处理两方面介绍了磨粒流加工技术的应用。     

超硬材料在精密加工中的应用现状与展望

文章主要介绍了超硬材料在汽车、空调压缩机、航空航天、半导体、轴承、5G手机陶瓷背板、金刚石微粉深度加工以及生物医疗精加工等方面的应用现状,分析对比了国内外产品的差异,认为国内超硬材料应用在粗加工方面优势明显,精加工方面差距较大。存在高端产品创新力度不强和上下游、产学研协同不足等问题,提出要加强基础研究和产品稳定性和针对性研究。预计国内超硬材料近几年在5G手机陶瓷背板加工、PCD、PcBN等方面将取得重大突破;国内精密加工产品会实质性进入汽车整车厂;政府和企业将会加大金刚石工具在半导体加工领域的投资和研发力度;超硬材料在航空航天、生物医疗领域的应用会加速。     

精密金刚石砂轮的制造、修整及其磨削机理研究进展

精密金刚石砂轮被广泛应用于各种硬脆性材料,如石材、玻璃、陶瓷、磁性材料、半导体材料等各种晶体材料的精密加工.精密金刚石砂轮的制造及其加工各种硬脆材料的磨削机理受到广泛的关注.文章综述了精密金刚石砂轮的制造、修整和磨削机理的研究状况.     

磨损颗粒分析技术在发动机磨损故障监测中的应用

磨粒分析技术主要包括光谱分析、铁谱分析、自动磨粒分析和扫描电子显微镜-能谱分析技术等,合理、有效地利用这些分析技术对发动机传动润滑系统使用油液中的磨损颗粒进行监测,能够及时发现传动润滑系统存在的早期磨损故障隐患,揭示磨损机理,确定发生磨损的部位,有助于防止磨损故障的发生。实践表明,光谱分析测定的磨损金属或污染元素含量异常(或达到经验值)时,应采用自动磨粒分析技术对磨损颗粒进行进一步的分析;当异常磨损的大颗粒增多时,需采用铁谱分析技术对磨损类型进行判断;同时,结合扫描电子显微镜-能谱分析技术分析异常磨损颗粒的材质,准确确定磨损部位,达到预先诊断的目的。     

第三代半导体材料SiC平坦化技术的研究现状

在半导体工业中,SiC由于化学性能稳定、导热系数高、热膨胀系数小、耐磨性能好等优良特性,成为了该领域最有发展前景的材料之一。然而,SiC材料硬脆性和化学惰性的特点,针对它的平坦化一直是SiC单晶材料制造的难点并在一定程度上制约着半导体芯片集成技术的发展。为获得理想的表面质量、实现有效的材料去除和平坦化加工,国内外学者提出了许多加工方法。本文结合超光滑表面抛光加工的目标,主要针对加工精度和平坦化加工效果较好、应用较广的磨粒加工、化学机械抛光、磁流变抛光方法的原理特点及存在问题进行归纳分析。     

cBN刀具的结构形式

随着机械制造业的高速发展,越来越多的难加工材料和超硬材料被广泛应用,随之机械加工刀具也面临严峻的考验,研发各种耐磨性好,热稳定性强,抗冲击性优良的超硬切削刀具是必然趋势。高效加工、硬加工、干式加工、超精密加工和新型难加工材料加工是刀具行业的发展方向,cBN刀具作为目前加工高硬度难加工的黑色金属材料最具优势的刀具材料,是未来实现精密和超精密加工的必备刀具。     

Investigation on high-shear and low-pressure grinding characteristics for zirconia ceramics using newly developed flexible abrasive tool

Zirconia ceramics is widely employed in medical, chemical and aerospace domain due to its excellent combination of physical and chemical attributes. However, high hardness and brittleness property have limited its application in manufacturing industries. Therefore, the present work aimed at development of a flexible abrasive tool based on concept of liquid body armor with large ratio of tangential grinding force to normal grinding force in order to enhance the surface processing quality of zirconia ceramics. A flexible body-armor-like abrasive tool was developed. Fundamental dynamic simulation and micro material removal processing at high-shear and low-pressure grinding conditions was analyzed. A multi-group of grinding experiments were carried out on an industrial robot platform for zirconia ceramic workpieces to validate the grinding performance of flexible body-armor-like abrasive tool. The surface roughness, surface morphology, grinding force and grinding temperature were investigated. At the optimal grinding condition, the surface roughness (Ra) of the workpiece was reduced by 91.8% and decreased from 110 nm to 9 nm. The scratches from the surface of the workpiece vanished and uniform grinding textures were left. The experimental results revealed that the developed flexible body-armor-like abrasive tool could achieve ultra-precision grinding of zirconia ceramics.     

金刚石固结磨料研磨K9玻璃的研究

为提高光学材料的研磨效率与质量,提出一种亲水性固结磨料研磨方法.采用图形转移与UV固化工艺,将粒径为5～10 μm的金刚石磨料固结于亲水性光固化树脂中,制备固结磨料研磨抛光垫(FAP).选取工件的材料去除率(MRR)和表面粗糙度(Sa)来评价研磨的加工性能.对比研究了在相同粒径磨粒下的游离磨料研磨、固结磨料丸片研磨、及亲水性FAP研磨三种不同方法对K9光学玻璃的加工性能.实验结果表明:采用FAP研磨K9玻璃,MRR为350 nm/min,表面粗糙度Sa为3.24 nm,达到了精研的加工效率和抛光的表面质量.提出了固结磨料抛光丸片和亲水性FAP的加工模型,以及亲水性FAP的自修整机理.     

PVD涂层阶梯杆的磁粒研磨加工研究

为了改善PVD(Physical Vapor Deposition)涂层阶梯杆的表面质量,实验中采用磁粒研磨的方法对阶梯杆进行磨削加工,并对实验参数进行优化,得出最佳磨削加工参数。结果表明,优化后的实验参数为:磁性磨粒的粒径大小为250μm,车床主轴转速为750 r/min,加工间隙为3 mm。用优化后的参数对阶梯杆进行磨削加工40 min,阶梯杆表面粗糙度从原始的Ra 1.35μm降低到Ra 0.26μm,阶梯杆表面光洁度有明显提高。     

Parameter optimization of ultrasonic vibration polishing K9 optical glass based on ultrasonic atomization

To further improve the surface finish and processing efficiency of optical components, ultrasonic vibration technology is frequently combined with conventional processing and the process parameters that play a critical role in this composite processing are identified. This research proposes an ultrasonic vibration polishing method based on ultrasonic atomization (UA-UVP). The polishing performance of K9 optical glass is increased by ultrasonic atomization (UA) assisted by polishing solvent for ultrasonic vibration polishing (UVP). Orthogonal experiments are used to study the effects and variation laws of the flow rate of ultrasonic atomization (Q), the gap distance between the polishing tool and workpiece (G), ultrasonic electro spindle speed (W), abrasive particle size (D) and ultrasonic amplitude (A) on surface roughness (SR) and material removal rate (MRR), respectively. When these two polishing characteristics are considered together, the optimization of polishing parameters becomes complicated. Therefore, the principal component analysis (PCA) and grey relational analysis (GRA) methods were employed to the optimal experimental combination as Q:18 ml/min, G: 5 μm, W: 4000 r/min, D: 0.5 μm, A: 8 μm. The experimental results showed that Ra and MRR were measured as 10.466 nm and 0.473*10^8 μm³/min, respectively. Compared with the best experimental combination of orthogonal experiments, the improvement rates of SR and MRR were 26.65% and 25.80%, respectively. Overall, the application of ultrasonic vibration technology contributes to enhancing the uniform distribution of polished abrasive particles and improving the polishing characteristics.     

Influence of process conditions on preparation of CBN/Fe-based spherical magnetic abrasive via gas atomization

To meet the demand for high-performance magnetic abrasive particles (MAPs) for finishing of difficult-to-machine materials, CBN/Fe-based spherical composite MAPs were prepared via gas atomization under different process conditions. The effects of nozzle type (single-stage and two-stage), second-stage gas pressure (2, 4, 6, and 8 MPa), and the grain size of the CBN abrasive (W7 and W40) on the MAP quality were studied. The MAPs were analysed through scanning electron microscopy and energy-dispersive spectroscopy. The results indicate that the quality of MAPs prepared using two-stage atomizing nozzles is better than that of MAPs prepared using single-stage nozzles. When the second-stage gas pressure was 6 MPa, the prepared MAPs had the best sphericity, and the CBN abrasive was embedded uniformly and densely on the surface of the iron matrix. For MAPs with the same particle size, the iron matrix wrapped more effectively around CBN abrasives with smaller grain sizes. This research is can serve as a methodological reference for understanding the preparation of ceramic/metal-based spherical composite MAPs via gas atomization.     

Wear characteristics of single-layer cBN abrasive tools using ultrasonic vibration–assisted induction brazing techniques

Single-layer brazed superhard abrasive tools have been widely employed in grinding of difficult-to-machine materials in aerospace, aiming at the improvement of the grinding performance and quality. However, the chemical metallurgical reaction during conventional induction brazing (CIB) is severe, and the brazing quality is poor, resulting in a rapid wear and thus reducing service life of abrasive tools. In this case, the single-layer brazed cBN abrasive tools were fabricated using ultrasonic vibration-assisted induction brazing (UVAIB) technology, and the wear comparative experiments of Ti–6Al–4V alloys was carried out using UVAIB and CIB abrasive tools. Results indicate that compared to the CIB abrasive tool, the UVAIB abrasive tool has the higher average exposure height of abrasive grains, lower grinding forces and more stable grinding force ratio during wear processes. Meanwhile, the UVAIB abrasive tool has a slowly decreased exposure height of abrasive grains, a superior wear state and low proportion of macro-fracture as the material removal volume raises. In addition, UVAIB abrasive tool possesses micro-cracks at the top of abrasive grains, leading to micro-fractures of abrasive grains to improve the self-sharpening ability and grinding performance.     

常温下重质碳酸钙的研磨改性一体化工艺研究

在粒径为45 μm重质碳酸钙的浆料中加入硬脂酸,利用研磨改性法,在研磨粉碎的同时制备了改性碳酸钙浆料,烘干粉碎后再对碳酸钙干粉进行改性。利用激光粒度分析等手段分别对碳酸钙干粉的粒度、表面活化度、吸油值、白度做了研究。结果发现,常温下可以实现重质碳酸钙研磨改性一体化工艺。研磨后碳酸钙颗粒的粒径由45 μm降至2 μm。随着硬脂酸的添加量逐渐增加,重质碳酸钙的活化度增加,吸油值下降。当硬脂酸的添加量增至2%（质量分数）后,重质碳酸钙的活化度超过98%,吸油值降至0.267 g/g。重质碳酸钙研磨改性一体化工艺有利于降低重质碳酸钙的生产成本,增加产品的竞争力。     

Ultra-precision finishing of low expansion ceramics by compliant abrasive technologies: A comparative study

Advanced ceramics have many attractive features such as high stability and wear resistance that find broad applications in various fields, e.g. optics, aerospace, etc. However, the accompanying difficult-to-machine property with complex geometry brings great challenges to the commonly used laser machining and rigid wheel based grinding in industry. To achieve optical surface quality with surface roughness below 10?nm Ra, three promising ultra-precision compliant machining technologies using adaptive elastic tools are presented in this paper, including bonnet polishing, compliant pitch polishing and shape adaptive grinding with fine grain size. A comparative study was conducted by machining three different low thermal expansion ceramics while continuously increasing attack angle, spindle speed and tool offset across rectangular regions. Material removal rate (MRR) and surface roughness (Ra) with respect to different process conditions are compared. With sufficient data, the processing ability using above three compliant machining technologies is summarized based on the MRR-Ra plots for different ceramics. In addition, microscopic observation and X-ray diffraction analysis are conducted to characterize differences in material behavior.     

Morphological evolution and grinding performance of vitrified bonded microcrystal alumina abrasive wheel dressed with a single-grit diamond

Dressing experiments under different conditions were carried out on a vitrified bonded microcrystal alumina abrasive wheel with a single-grit diamond dresser. The grinding performance of the as-dressed abrasive wheels was investigated. The dressing force, grinding force and the surface morphology of abrasive wheel and machined workpiece were studied to shed light on the relationship among the dressing processing vectors, morphology of abrasive wheel and the grinding performance. The results obtained show that the dressing forces increase with the increasing volume of the abrasive wheel material removed per unit time. The sensitive analysis reveals that the dressing feed speed take a greater effect than the single dressing depth on the dressing force. The self-sharpness of vitrified bonded microcrystal alumina abrasive wheel brings into some functions under certain dressing conditions, but a deep dressing depth would lead to an excessive abrasive self-sharpness, i.e. abrasive grits fall off and embed into the workpiece surface.     

粉磨工艺对水泥颗粒分布及其混凝土性能的影响

研究了不同粉磨工艺系统磨制水泥的颗粒分布、粉磨电耗、标准稠度用水量、与减水剂相容性及其配制的混凝土强度、耐磨性、抗碳化性能的差异;针对我国混凝土行业的现状,从混凝土性能的角度出发,探讨了现阶段各种水泥粉磨工艺的特点。研究结果表明,水泥粉磨工艺系统的效率越高,水泥的颗粒分布越集中,水泥的标准稠度用水量增大,与减水剂相容性变差,在缺乏良好的掺合料进行颗粒分布校正的前提下,所配制混凝土的强度、耐磨性及抗碳化性能均有所下降。