陶瓷cBN砂轮基体材料及截形选择

陶瓷cBN高速砂轮一般都采用金属基体材料,为了保证基体强度,改善应力分布,获得安全有效的砂轮定心及安装形式,对其基体材料进行选择和截形优化非常关键.文章对各种金属材料的物理机械性能进行了对比,确定了适合高速磨削的砂轮基体材料;同时,列举了三种规格的砂轮基体,可以根据需要进行选择.     

钎焊金刚石微刃砂轮的制备及其磨削AlSiC的性能研究

钎焊金刚石砂轮具有磨粒结合强度高、出刃高、不易堵塞等优点。但细粒度钎焊金刚石砂轮的制备还存在难点。文章提出了一种钎焊金刚石微刃砂轮的制备方法:使用脉冲激光在有序排列钎焊金刚石砂轮表面加工出微刃结构,并研究了钎焊微刃砂轮加工70%SiC体积分数的AlSiC复合材料的磨削性能,对比了钎焊金刚石微刃砂轮和普通钎焊金刚石砂轮在不同磨削参数下的磨削力。研究发现,钎焊金刚石微刃砂轮的磨削力比普通钎焊金刚石砂轮的小;通过观察被加工材料的表面微观形貌,相比普通钎焊砂轮,钎焊金刚石微刃砂轮可以获得更好的AlSiC复合材料磨削表面质量。     

超高速点磨削砂轮的设计与磨损仿真

文章详细阐述了超高速点磨削中砂轮的应用状况,介绍了超高速点磨削砂轮的应用范围,通过这种新型砂轮的基体和cBN磨料层的设计,介绍了砂轮基体和磨料层的设计原则,介绍了cBN磨料层中粗磨区和精磨区中的磨料对于去除材料的磨削效率的作用,引入了这种新型砂轮中的粗磨削区倾角的概念,推导出粗磨削区倾角的大小在超高速点磨削中对于磨削参数的影响趋势,并且设计了适用于本实验的粗磨削倾角的大小,制造了适用于超高速点磨削实验的砂轮,介绍了由于粗磨削倾角的存在对磨削时切屑的流动状态及倾角对于磨削效率的影响,利用超景深显微镜观测砂轮磨料层的微观结构,分析表面的气孔率和cBN磨料的分布状态,通过磨粒的分布预测加工后的表面形貌,仿真出新型砂轮的磨损趋势,得出了有关超硬磨粒层制造和磨损的相关结论,砂轮的制造与设计直接关系超高速点磨削的广泛推广,为实现超高速点磨削的高效率和高精度的加工提供必要的设备支持,为其理论研究提供可供参考的依据。     

铜基钎料真空钎焊镀钛金刚石

利用Cu-10Sn-5Ti钎料粉末在钢基体上真空钎焊镀Ti金刚石.考察了钎焊温度对金刚石与钢基体结合强度的影响,分析了Ti镀层在金刚石钎焊过程的作用.结果表明:当钎焊温度为900～920℃时,可实现金刚石、铜基钎料与钢基体之间的强力冶金结合;且金刚石由于镀Ti层的保护隔离作用,大大降低了热损伤和石墨化,金刚石的晶型完整...     

真空钎焊无镀覆和镀钛金刚石磨粒的实验研究

以Ni-Cr合金为钎料,对无镀膜和表面镀钛两种金刚石进行钎焊研究,实现了金刚石与钢基体的高强度连接.SEM和EDS等分析结果表明在一定的钎焊温度、时间及真空度下,钎料与两种金刚石均形成化学冶金结合.钎焊后无镀膜金刚石表层碳化物沿金刚石法线方向生长;而镀钛金刚石表层碳化物的生长方向为金刚石切线方向.对两种式样进行磨削实验发现,Ni-Cr合金对金刚石有很强的"把持力",在磨削过程中金刚石出现宏观破损,无金刚石脱落现象.     

钎焊金刚石砂轮磨削YG8硬质合金的试验研究

采用细粒度钎焊金刚石砂轮(粒度100/120)对YG8硬质合金进行磨削性能评价。结果表明:法向磨削力和切向磨削力均随着砂轮线速度的增大而减小、随着工件进给速度和磨削深度的增加而增大,其中磨削深度对磨削力的影响最大;法向磨削力与切向磨削力存在线性关系,其比值约为4.17;砂轮/工件接触面符合库伦摩擦定律,滑动摩擦系数为0.24;磨削后工件表面粗糙度随着砂轮线速度的增加而下降、随着进给速度和切深的增加而增加,其垂直方向粗糙度0.6~0.9μm,平行方向粗糙度0.05~0.2μm。     

钛合金加工方法的多样性

钛合金是以钛(Ti)为主要成分的合金,并含铝、钒、铁和锰等元素以提高其性能。钛合金被认为是轻质、高强、耐热材料的典型代表,使得其广泛应用于工程领域,最具代表性的是航空航天领域。然而,由于强度高、导热系数低和化学活性高等特点,钛合金的机械加工难度较大,中外学者对此展开了一系列研究,提出了多种多样的钛合金切削磨削加工技术。文章简要介绍了金刚石砂带、球形固结磨料磨头、聚晶超硬材料刀具以及不同cBN砂轮(钎焊砂轮、电镀砂轮和陶瓷砂轮)等对钛合金的加工。     

内圆磨削平面和孔的组合工具

使用cBN工具对传动元件的平面和孔进行内圆磨削是一项创新。从加工设备上的轴开始，要求要明显降低单个被加工零件的成本。采用将孔和平面加工结合在一起，并且通过将氧化铝磨料改换成cBN磨料增长修整周期的方法，开发出了钢基体陶瓷结合剂cBN专用磨削工具，它分两个部分，用来对左右两边进行内圆成型磨削，用圆周面磨削孔，用端面磨削内部平面。开发这种cBN工具的一大难点是需要确保磨削接触点有足够的冷却液供给。在该方法中，痦削孔和平面时，砂轮和工件的接触面积很大，并且极难找到通往接触区的通道，     

一种拉刀用陶瓷结合剂cBN砂轮的制备及应用

陶瓷结合剂cBN砂轮是一种适用于高速高效磨削的工具。研究制备了一种磨削拉刀用的陶瓷结合剂cBN砂轮,通过研究砂轮在磨削拉刀方面的应用,发现使用该砂轮不仅使磨削效率得到了提高,也使得磨削加工精度和表面磨削质量得到了提高。当砂轮的硬度质量CPK均在1.33以上时,砂轮表面稳定性优良,使得砂轮在磨削工件拉刀时所测量的刃面粗糙度及刀刃间的尺寸公差CPK均大于1.67,可以看出经砂轮磨削后的拉刀一致性非常优秀,达到了国际先进水平,生产的拉刀可替代国外进口产品。     

陶瓷结合剂cBN高速砂轮受力分析

陶瓷结合剂cBN砂轮工作速度一般在80m/s以上,为了保证砂轮的安全运行,砂轮本身必须具备一定的强度.文章分别探讨了陶瓷基体和铝合金基体的cBN砂轮,并进行了空转状态下的受力分析,分析结果表明,陶瓷基体在80m/s的工作条件下,很难满足要求,铝合金基体能有效提高砂轮的工作速度,降低对工作层的强度要求.     

Microstructural characteristics and mechanical properties of diamond grinding wheel brazed with modified Ni–Cr–W alloy using continuous tunnel furnace

A novel brazing technology using a continuous tunnel furnace with modified Ni–Cr–W filler alloy is presented to achieve brazed diamond grinding wheels with high efficiency and low thermal damage. Mechanical characterization confirms that the static pressure strength and impact toughness of the diamond brazed using the new brazing technology are 22.2% and 10.5% higher, respectively, than those of diamond brazed using conventional vacuum brazing technology, respectively. Raman spectroscopy reveals that the degree of graphitization of diamond brazed with the novel brazing technology is decreased. In addition, residual stress is reduced by 23% after brazing with new brazing technology. Scanning electron microscopy is used to observe interfacial microstructure of brazed diamond. The elemental distribution and phase composition of brazed joint are analyzed by energy dispersive spectroscopy and X-ray diffraction. The results demonstrate that metallurgical bonds are formed between diamond and modified alloy, endowing strong bonding force to diamond abrasives. Tungsten (W) can react with diamond and modified alloy to form W–C compounds and bonding phases. Besides, W combines with certain amount of Ni element to reduce graphitization degree, improve integrity and decrease residual stress of brazed diamond. Compared with commonly utilized vacuum brazed grinding wheel, grinding test indicates that service life of grinding wheel, prepared by new brazing technology, is improved. The machining efficiency is increased by 42.4% and the abrasive invalidation rate is reduced by 33.7%. In conclusion, the diamond grinding wheel, prepared by new brazing technology, exhibits superior performance.     

Fabrication of porous structure vitrified bond diamond grinding wheel via direct ink writing

Porous vitrified bond grinding wheels with complex structure, high porosity, controllable pore size have fundamental application in high efficiency and precision grinding of hard and brittle materials. In this paper, direct ink writing (DIW) is proposed to fabricate three kinds of grinding wheels, including solid structure, triangle structure, and lattice structure. Moreover, the rheological property of ceramic ink with different doses of xanthan gum (XG) solution was investigated to ensure printability, demonstrating 3% XG solution can meet requirements. Additionally, the effect of sintering temperature and pore former (PMMA) contents on size shrinkage rate, morphology, mechanical strength, and porosity et al. were studied. The results indicate that the diamond grinding wheel with 30 vol% PMMA and sintered at 670 °C possess the best comprehensive performance. Besides, grinding performance was evaluated by surface morphology, surface roughness, and material removal rate. Among the DIW-fabricated wheels, triangle structure grinding wheel and lattice structure grinding wheel possess a higher material removal rate than solid structure grinding wheel. Therefore, the porous structure grinding wheels fabricated by DIW present the advantage of controllable porosity, excellent self-sharpening ability, and higher bond strength, which may pave the way for designing a new generation vitrified bond diamond grinding wheel.     

微波烧结陶瓷结合剂金刚石砂轮研究

为了提高陶瓷结合剂金刚石砂轮的性能,采用微波烧结技术,通过一系列试验,分析了陶瓷结合剂金刚石砂轮的微波烧结温度、陶瓷结合剂含量和金刚石磨料粒度对其性能的影响。结果表明:微波烧结温度是影响陶瓷结合剂金刚石砂轮性能的最主要因素,远超其余二者;陶瓷结合剂金刚石砂轮试样的洛氏硬度和抗弯强度在740 ℃时达到极大值且气孔率较小,此时洛氏硬度为66 HRB,抗弯强度为76.5 MPa,气孔率为17.8%;由微观组织观察可知陶瓷结合剂金刚石砂轮在740 ℃时可以实现陶瓷结合剂对金刚石磨料的均匀包裹,并且气孔较少。     

CBN grain wear during eco-benign grinding of nickel-based superalloy with oscillating heat pipe abrasive wheel

Cubic boron nitride (CBN) has high hardness and superior thermal conductivity, and it was used to fabricate an oscillating heat pipe abrasive wheel (OHPGW) for the eco-benign grinding of hard-to-machine materials. Furthermore, the wear behavior of the CBN grains and the related lifecycle of the OHPGW are important. In this study, a comparative analysis was conducted to reveal the wear behavior of CBN grains on OHPGWs and conventional wheels. Under the enhanced heat transfer effect of the OHPGW, the CBN grain wear behavior, development of the CBN protrusion heights, and the ground surface quality were investigated. The CBN grains on the abrasive wheel experience initial, stable, and fast wear periods in conditions of attrition, micro-fracture, and macro-fracture. Owing to the low grinding heat and temperature acting on the OHPGW, the CBN grains mostly undergo attrition during the stable period, while CBN grains on the conventional wheel mainly undergo micro and macro-fractures. As the wear of the CBN grains progressed, the average protrusion height of the CBN grains decreased. The scattering of the protrusion height distribution decreased at first and then increased when entering the fast wear period. Consequently, the surface topography and roughness initially improved and then deteriorated with the development of the protrusion height distribution of the CBN grains.     

工业陶瓷超声辅助加工技术研究

陶瓷材料具有耐高温、硬度高、绝缘性好的优良性能,在航空航天、军事医疗、电子信息等领域具有广泛的应用。旋转超声辅助加工的刀具磨损小、材料去除率高、加工精度高,在工业陶瓷精密加工领域取得了较好的运用。本文以常用的石英陶瓷和氮化硅陶瓷为加工对象,进行了表面磨削及钻孔试验研究,通过宏观形貌观察、测量表面粗糙度值、工件及刀具微观形貌分析,确定了PCD砂轮结合超声辅助磨削加工,可以得到较好的表面加工质量。开展了石英陶瓷凹槽面、平面及过渡面的磨削加工试验,取得了较好的表面形貌;利用不同类型的砂轮加工氮化硅陶瓷孔,从而确定高强度的金刚石磨头是加工硬性材料的最优砂轮。     

Preparation of a novel vitrified bond CBN grinding wheel and study on the grinding performance

The vitrified bond CBN grinding wheels are characterized by high efficiency, high precision, and low environmental pollution. In recent years, the vitrified bond CBN grinding wheel has been widely used in manufacturing industries such as aerospace, automotive, and machine tools. In this study, a novel vitrified bond formulation containing nano SiO₂ and nano CeO₂ is selected to prepare the grinding wheel. The grinding experiments on 45# steel and YG20 alloy indicate that the grinding performance of the nano vitrified bond grinding wheel is significantly better than that of the conventional vitrified bond grinding wheel. The introduction of nano SiO₂ and nano CeO₂ greatly improves the machining performance of the vitrified bond CBN grinding wheel.     

Grinding performance improvement of laser micro-structured silicon nitride ceramics by laser macro-structured diamond wheels

Silicon nitride ceramics are widely used in various industrial fields because of their excellent characteristics: high hardness, high elastic modulus, abrasion resistance, and high heat resistance. Diamond wheel grinding is the predominant and most productive method to machine silicon nitride ceramics. However, a lot of heat is generated due to high friction between a diamond grinding wheel and extremely rigid silicon nitride during grinding. This causes surface/subsurface damage, wheel wear, etc., which impairs the surface quality of silicon nitride. This impairment can restrict the use of silicon nitride ceramic components. To improve the surface quality and service life of grinding wheels, a laser macro-micro combination structured grinding (LMMCSG) method was presented. The results indicated that the grinding force ratio and surface roughness when using LMMCSG were respectively 31% and 40% lower than the grinding force ratio and surface roughness when using conventional grinding. Moreover, the LMMCSG method effectively reduced the wheel wear and workpiece subsurface damage.     

The mechanism investigation of ultrasonic roller dressing vitrified bonded CBN grinding wheel

To clarify the ultrasonic roller dressing mechanism of the vitrified bonded cubic boron nitride grinding wheel (V-CBN), the collision number model between the diamond dresser and CBN grits was established based on the geometric and kinematics analysis. The influence of each dressing parameter on the collision number was analyzed and discussed. The grinding experiment was performed on the bearing raceway with the dressed V-CBN grinding wheel, results obtained discovered that there was an inverse relationship between the collision number and the surface roughness and runout of the workpiece. Additionally, compared with conventional dressing, ultrasonic dressing has the advantage in improving the surface quality because it can produce more collision numbers and raise grit retention. In words, the collision number can be used to predict the dressing effect, which provides a reference for formulating an appropriate dressing process for V-CBN to improve the workpiece surface quality and production efficiency.     

砂轮用聚酰亚胺胶粘剂的研究现状

聚酰亚胺树脂是一种耐高温、高强度的工程塑料,它可用于制造金刚石砂轮,使砂轮的耐热性得到改善。本文从耐高温性、可加工性、高粘结性、耐磨性等方面概述了聚酰亚胺作为金刚石砂轮结合剂的优越性,实践证明,聚酰亚胺胶粘剂具有优异的耐热和高温粘接性能,用其制造的金刚石砂轮耐磨性优于酚醛砂轮。     

Investigation on preparation of composite vitrified bonding ultrafine diamond grinding wheel and machining of PcBN inserts

The grinding of polycrystalline cubic boron nitride (PcBN) is hard owing to its high hardness and superior wear-resistance capacity. Machining of PcBN tools via vitrified diamond grinding wheels with a size above 10 μm may lead to brittle fracture instead of a ductile machining because of the poor toughness of cubic boron nitride. A uniformly dispersed M0.5/1.5 diamond grinding wheel with a composite vitrified bonding was fabricated to improve the surface roughness of PcBN inserts. It is demonstrated that the preparation of composite vitrified bonding with various additions of vitrified bonding produced by the melting-quenching technique (VB-MQ) has little effect on the performance of vitrified bonding, such as bending strength, CTE and phase and achieves the uniform dispersion of M0.5/1.5 diamond as the addition of VB-MQ is no greater than 50%. Both the grinding ratios and the surface roughness of PcBN inserts are enhanced.