氮化硅陶瓷球研磨去除机制试验与仿真研究

为研究研磨过程中氮化硅陶瓷球的材料去除形式及磨损行为,结合陶瓷材料动态压痕断裂力学理论,进行陶瓷球研磨加工试验,采用超景深三维显微镜和扫描电镜对研磨后陶瓷球表面进行观察,同时建立单颗金刚石磨粒冲击作用有限元模型并进行仿真研究。试验结果表明:氮化硅陶瓷球表面材料去除以脆性断裂去除和粉末化去除为主,陶瓷球表面残留有大量贝壳状缺陷和呈簇状随机分布的粉末化材料区域;研磨过程中,陶瓷球表面存在擦伤、划伤和凹坑等缺陷;磨粒冲击作用时,表面材料会受微切削作用产生破碎去除,同时也会受挤压作用产生脆性断裂去除,当磨粒以滚动方式作用在陶瓷球表面时,陶瓷球表面更容易形成粉末化去除,且材料去除率更高。仿真结果表明:各磨粒冲击作用方式产生的最大等效应力由大到小的顺序为滚动磨粒变切深、滚动磨粒定切深、磨粒挤压、滑动磨粒定切深,其中,滚动磨粒变切深产生的亚表面裂纹最深。     

基于不同磨料的氮化硅陶瓷球精研工艺研究

为探究磨料对氮化硅陶瓷球精研加工的影响,从而提高氮化硅陶瓷球的表面质量和材料去除率,以基液种类、磨料种类和研磨盘转速为主要影响因素设计正交试验,并分析各因素对表面粗糙度Ra的影响程度。以表面粗糙度Ra和材料去除率为评价指标,通过单因素试验优化研磨参数。根据正交试验结果,得到精研加工过程中各影响因素对于表面粗糙度Ra的影响程度,从大到小排列依次为:磨料种类>基液种类>研磨盘转速。综合考虑陶瓷球精研加工的要求,确定最佳的研磨参数组合为:煤油基液、碳化硅磨料以及150 r/min的研磨盘转速。在金刚石、碳化硅、氮化硼、氧化铬和氧化铁这5种磨料中,氧化铁磨料修复粗研过后的氮化硅陶瓷球表面缺陷的效果最好。     

陶瓷球材料去除形式的实验研究

文中探讨了陶瓷球研磨过程中工艺参数对陶瓷球表面材料去除形式的影响,利用球-盘式陶瓷球单球磨损试验装置,对不同研磨液磨料浓度和压力条件下对氮化硅陶瓷球的磨损形式进行了研究,以确定各种加工条件下的材料磨损形式.     

SrTiO3陶瓷基片集群磁流变研磨加工表面特性研究

采用集群磁流变效应研磨加工工艺进行SrTiO3陶瓷基片研磨加工,分析了研磨盘材料、磨粒种类、研磨压力和磨粒团聚等因素对SrTiO3陶瓷基片表面粗糙度和表面完整性的影响。 结果表明:磁流变效应研磨工作液中的SiC、Al2O3和CeO2等磨料的大尺寸磨粒在SrTiO3陶瓷基片研磨加工表面产生的局部大尺寸划痕破坏了加工表面的完整性;采用铸铁研磨盘和SiO2磨料的磁流变研磨工作液研磨加工后,原始表面粗糙度Ra从约1.7854μm下降到0.6282μm,并且表面完整,SrTiO3材料与SiO2磨料之间存在的化学机械研磨过程促进了研磨加工表面性能的改善;研磨压力也是影响研磨加工表面粗糙度和大尺寸划痕的主要因素之一,研磨压力取较小值(1.875kPa）为宜。      

表面织构陶瓷刀具切削性能研究

采用激光在Al2O3/TiC陶瓷刀具前刀面加工出不同的表面织构,制备出纳米织构陶瓷刀具及微纳米复合织构自润滑陶瓷刀具,并与传统陶瓷刀具进行干切削45淬火钢试验比较.结果表明:纳米织构陶瓷刀具不能够有效降低切削力、改善刀具黏结现象,但是可以减小刀具前刀面磨损凹坑,减少磨粒磨损;微纳米复合织构自润滑陶瓷刀具能够有效降低切削力,减小刀具磨损,改善刀具的切削性能.     

精研瘤的消除方法

超精研是轴承滚道的最后一道工序，其加工的质量直接影响轴承的成品质量。精研润是该工序产生的一种怒性表面缺陷，本文对精研瘤的成因以及消除方法提出了一些新的见解。一、精研瘤的成因精研启产生于轴承套圈沟道的超精研过程中，其形状是一种白色点状突起物。有研究认为是切屑与磨粉条和力强而产生。我厂用扫描电子显微镜对精研瘤的形貌及成分进行分析。1．精研瘤有一条慧星尾巴似的划痕，如同“富拉”逐渐切入工件表面，当研削力和摩擦阻力相平衡财，这颗“唐粒”就嵌入工件表面，成为精研瘤,2．在越精研沟道时，磨粒尺寸为10～14μm，而…     

氮化硅陶瓷球高效研磨加工工艺试验

氮化硅陶瓷球的高效研磨加工至关重要,在分析陶瓷球加工原理、加工方法及存在问题的基础上,以?4.762 5 mm氮化硅陶瓷球为试验对象,分析采用金刚石砂轮加工与传统V形槽研磨方法的差异。结果表明:采用金刚石砂轮进行陶瓷球粗磨工序加工能够大幅缩短加工时间,提高加工效率,降低劳动强度;能够消除传统V形槽研磨方法中易出现的顶窝、环带和碎球等缺陷;但金刚石砂轮加工出的陶瓷球直径变动量、批直径变动量及球形误差较大,为保证后续加工应适当加大留量。     

钢球制造工艺(3)

第四章 工艺过程、 留量及公差 一、钢球制造的工艺过程钢球制造的基本工艺过程大致如下: 球坯成形→去环带→粗磨→软磨→↓ 热处理→ 球坯成形→光球(或锉削→软磨)→硬磨→细研→精研(或抛光)→超精研。 1.一般工艺过程 ①主要工序:各种直径钢球的基本加工工序如表4-1所示。     

水压马达仿生非光滑表面配流副摩擦磨损研究

为探寻低速大扭矩水压马达仿生非光滑表面配流副摩擦磨损性能,采用精密加工技术在碳纤维增强PEEK试样表面加工出不同形状的仿生非光滑凹坑,与316L不锈钢形成摩擦副,利用MMD-5A多功能摩擦磨损试验机在海水润滑条件下,对其在不同面积占有率下的摩擦因数、磨损率等参数进行测试,考察其凹坑面积占有率对摩擦副摩擦磨损的影响,利用OLYMPUS OLS3100激光共焦显微镜对磨损表面进行分析。研究表明:在海水润滑条件下,下试样CF/PEEK在磨擦过程中主要发生了犁沟效应和磨粒磨损,仿生非光滑表面的凹坑可以有效存储磨粒,减轻磨粒磨损,进而起到减摩效果。面积占有率为15%的圆锥形凹坑仿生非光滑表面更利于存储磨屑,因而摩擦因数最低,减磨效果最好。     

“02”级精度微型钢球试制情况介绍

试制的“02”级精度别1/16的钢球,钢球的精度能稳定地达到如下指标: 真球度 0.1微米 尺寸互相差 0.1微米 表面光洁度 13级以上 表面缺陷 用干涉法放大490倍检查, 整个钢球表面的缺陷数量 不多于4个,缺陷处的粗 糙度不低于12级。精研工序的生产率可达1500个/8 小时 “02”级精度钢球与“0”级精度钢球的加工工艺大致相同,“02”级精度钢球加工的主要关键在于精研工序。精研采用的机床是利用金相磨片机改装的立式研球机,机床刚性好,振动小。精研前的工件必须严格控制尺寸及公差;加工规范要适当;研磨盘必须达到规定的技术要求;研磨油膏及精研板必须清洁,油膏氧化铬颗粒要细。附表2个。     

铌酸锂晶体的研磨亚表面损伤深度

针对光学材料研磨过程引入的亚表面损伤层(SSD)深度对工件的抛光工序效率和表面质量的影响,探索了光学材料在研磨过程中的亚表面损伤规律。采用角度抛光的方法测量了软脆材料铌酸锂(LN)晶体的损伤层深度,分析了研磨方式、磨粒粒径和研磨压力对工件亚表面损伤层的影响规律。结果表明:研磨方式对损伤缺陷的影响最为显著,相同研磨条件下游离磨料研磨后的损伤层深度约为固结磨料研磨的3~4倍,游离磨料研磨后工件亚表面存在多处圆弧形裂纹,固结磨料研磨后主要显现细小裂纹和"人"字型裂纹;当磨粒粒径从W28下降到W14后,游离研磨的亚表面损伤层深度下降至原来的45%,而固结研磨的损伤层深度下降至30%;另外,研磨压力的降低有利于减小工件的亚表面损伤。该研究对LN晶体研磨方式及研磨工艺的选择具有指导意义。     

The particle size effect on abrasive wear of high-chromium white cast iron mill balls

Granite grinding tests, under dry and wet conditions, were performed to assess the influence of abrasive particle size to the wear behavior of martensitic high-chromium white cast iron mill balls. The tests were performed, at first, using raw granite particle sizes between 0.074 and 19.1 mm, and then with coarse and fine granite fractions obtained after screening the raw granite in a 3.36 mm sieve. It is demonstrated that the relative particle/ball size relationship is the determining parameter to ball wear. The highest ball wear rates were observed for fine granite grinding under dry (120 mg/cycle) and wet (129 mg/cycle) conditions. The lowest wear rate (ca. 50 mg/cycle) was observed for coarse granite grinding (dry and wet). These different results were attributed to the different size relationships between grinding body diameter and granite particles size. For wet-grinding of raw granite, the mineral components may influence significantly the wear behavior. Feldspar can act as a bonding agent, gluing fine quartz particles to the coarse granite and to the balls surface and turning the dependence of the relationship between the relative sizes of ball and granite particle less important to the wear process. This explains why wet-grinding of raw granite results in a ball wear two times greater (106 mg/cycle) than dry-grinding (51 mg/cycle).     

Binder extrusion in sliding wear of WC-Co alloys

It has previously been proposed that preferential removal of the cobalt binder is an important mechanism in the abrasive wear of cemented carbides in the WC-Co family. It is here demonstrated that binder extrusion occurs also in metal-to-metal sliding wear contacts. The wear scar generated by sliding a hardened steel ball repeatedly over a polished WC-Co surface was studied by scanning electron microscopy. The extruded cobalt fragments accumulate at surface defects, such as cracks caused by the sliding loaded ball, and gradual microfragmentation of the carbide grains follows. The energy required to extrude the cobalt and to cause the gradual change in surface layer microstructure is provided by the frictional forces.     

The effects of ball surface condition in the micro‐scale abrasive wear test

The ball‐crater micro‐scale abrasive wear test can be applied to coated samples and small bulk samples. The surface condition of the ball influences the magnitude and the reproducibility of the measured wear coefficient. Use of a polished new ball in the test may give uncertain or anomalously low wear coefficients, particularly for relatively soft specimens. This effect is explained in terms of the ease of entrainment of abrasive particles into the contact area. Reproducible results are obtained with pre‐conditioned balls with slight surface pitting, and the use of such balls is recommended for routine testing. This revised version was published online in June 2006 with corrections to the Cover Date.     

研磨液对陶瓷球耐磨性影响的实验研究

本文利用往复式和微幅式摩擦磨损实验机,在陶瓷球和轴承钢构成的运动副间加入不同的研磨液,对陶瓷球在不同研磨液时的摩擦磨损性能进行了实验研究,实验结果为陶瓷球研磨加工过程中不同阶段研磨液的选择提供了数据。     

Corrosive and abrasive wear in ore grinding

The relative significance of corrosive and abrasive wear in ore grinding is discussed. Laboratory marked ball wear tests were carried out with magnetic taconite and quartzite under different conditions, namely dry, wet and in the presence of an organic liquid. The effect of different modes of aeration and of pyrrhotite addition on the ball wear using mild steel, high carbon low alloy steel and austenitic stainless steel balls was evaluated. Results indicate that abrasive wear plays a significant role in ore grinding in the absence of sulfides, and rheological properties of the ore slurry influenced such wear. The effect of oxygen on corrosive wear becomes increasingly felt in the presence of a sulfide mineral such as pyrrhotite. Wear characteristics of the three types of ball materials under different grinding conditions are illustrated.     

Development of magnetically assisted lapping process for nano-finishing of alumina balls

The advanced ceramics have emerged as a successful alternative to the conventional materials used in ball bearing industry. However, extreme hardness and lower toughness of the ceramic balls make their finishing a challenging task. To address this problem, a novel process is developed and results are presented in this article. The process is termed as magnetically assisted lapping (MAL) wherein the lapping and the polishing action are supported by magnetic levitation. The process parameters are identified. The capability of the process in terms of surface finish, roundness and material removal rate of alumina balls is assessed. The process is carried out in two stages. In the first stage, the main focus is on material removal and sphericity while the second stage focuses on achieving nano level surface finish. A very high material removal rate of 2.5 µm/min is achieved in the first stage. In the second stage, diamond abrasive powder (0.25–1 µm) mixed with silicone oil is used as a polishing medium for fine finishing of balls. The final surface finish of 20?nm and roundness of 0.23 µm is achieved which meets the requirement of G10 grade bearings (as per ISO3290). Atomic force microscope images show remarkable improvement of the surface up to 8?nm. The developed process is capable of producing nanometric finish in quite lesser time as compared to conventional and eccentric lapping processes. The underlying mechanism of material removal is proposed with the help of scanning electron microscope and atomic force microscope images.     

硬盘巨磁电阻磁头的超精密抛光工艺

硬盘巨磁电阻磁头的抛光可分为自由磨粒抛光和纳米研磨,在自由磨粒抛光中,精确控制载荷和金刚石磨粒的粒径,可以避免脆性去除实现延性去除。通过控制抛光过程中的抛光盘表面粗糙度、金刚石粒径大小及粒径分布和载荷等进行滚动磨粒和滑动磨粒比例的调控,获得较好的磁头表面质量和较高的材料去除率。在自由磨粒抛光阶段,先采用铅磨盘抛光,然后用锡磨盘抛光,以纳米研磨作为最后一道抛光工序对磁头表面进行研磨,获得了亚纳米级粗糙度的磁头表面。用两种工艺制作的纳米研磨盘进行加工,分别获得了0.37nm和0.8nm的磁头表面粗糙度,去除率分别为5.3 nm/min和3.9nm/min。