Fe-Al_2O_3磁性磨料制备新工艺

分别以还原铁粉和雾化铁粉作为磁性粉,刚玉粉为磨粒,高温无机粘结剂为胶粘剂,并对铁粉进行表面改性后,采用烧结法制备了四种不同的Fe-Al2O3磁性磨料;采用X射线衍射仪和扫描电子显微镜分析了磁性磨料的物相组成和外观形貌,测试了磁性磨料的研磨性能,研究了铁粉种类以及表面改性处理对磁性磨料性能的影响。结果表明:制备的磁性磨料主要由-αFe、Al2O3、Fe2O3、AlFeO3(、Al,Fe)7BO3(SiO4)3O3等相组成,其形状多为不规则的棱状颗粒;制备的磁性磨料均具有良好的研磨效果和较长的耐用度,研磨工件的表面粗糙度可达到0.15μm,使用时间达到24 min;采用还原铁粉比用雾化铁粉、用表面改性的铁粉比用未改性的铁粉所制备磁性磨料的研磨性能要好。     

烧结磁性磨料和粘结磁性磨料的对比研究

通过对烧结法制备磁性磨料和粘结法制备磁性磨料进行总体的分析比较，得出烧结磁性磨料的性能是明显优于粘结的，而且总的性价比也是高于粘结的。     

粘结磁性磨料制备及其研抛加工研究

采用粘结法制备磁性磨料,对磨料制备工艺进行了优化,确定了最终的工艺方案.通过实验对所制备的粘结磁性磨料进行了性能分析,结果表明磁性磨料粒度为40目时研磨效果最佳,用于模具钢的磁性研磨原始表面Ral.87微米经过4分钟加工可降低到Ra0.4微米左右;氧化铝磁性磨料比碳化硅磁性磨料具有更好的耐用度,持续研磨加工时间可达16分钟;研磨初期工件表面粗糙度快速降低,之后降低趋于平缓;采用由粗到细的磁性磨料分步加工可有效降低表面粗糙度值、缩短加工时间,原始表面Ra2.092微米经过40目、60目、80目磁性磨料各加工4分钟后粗糙度可以达到Ra0.11微米.     

SiC磁性磨料陶瓷颗粒增强相分布研究

以铁合金作为基体,刚玉粉为磨粒,在雾化快凝装置中采用气雾化快凝法制备不同粒度的磁性磨料;在经过镶嵌、研磨、抛光、酸洗之后,采用热场发射扫描电子显微镜(SEM)观察磁性磨料的剖面形貌,结果发现当陶瓷颗粒增强相为Al2O3时磁性磨料表层有大量均匀的硬质磨粒相分布,而当陶瓷颗粒增强相为SiC时磁性磨料中的硬质磨粒数量则很少,甚至没有陶瓷颗粒分布。以喷射沉积增强相分布模型为依据,分析研究SiC磁性磨料中陶瓷颗粒分布较少的原因,并提出解决方案。     

研磨硬脆材料的金刚石磁性磨料制备

运用化学复合镀法制备了用于硬脆材料研磨的金刚石磁性磨料。采用单因素实验方法研究了铁粉的装载量、金刚石磨粒的浓度以及机械搅拌的速度对金刚石相对含量的影响。通过石英玻璃的平面磁控研磨加工实验测试了制备的金刚石磁性磨料的研磨性能。结果表明,当铁粉的装载量为6 g/L,金刚石磨粒浓度为6 g/L,搅拌速度为300 r/min时,金刚石相对含量较高。金刚石磨粒在Ni-P合金镀层中粘结牢固,分散均匀。通过磁控研磨加工,石英玻璃的表面粗糙度快速地从0.709μm降低到0.138μm,证明了制备的金刚石磁性磨料具有较好的研磨性能。     

粘结法制备磁性磨料的研究

采用粘结法制备磁性磨料 ,并对各种磨料进行磁力研磨试验。研究磁性磨料的配比、粘结剂的选择以及粒度对不锈钢管 1Cr18Ni9Ti的材料去除量和表面粗糙度的影响。试验结果表明 ,使用环氧树脂A制备的磁性磨料具有较好的研磨效果 ,磨料中Fe与白刚玉粉较为合适的配比是 4∶1,磨料的粒度为 80目时研磨效果较佳。     

气雾化快凝磁性磨料陶瓷颗粒增强相分布的研究

以铁合金作为基体,刚玉粉为磨粒,在雾化快凝装置中采用气雾化快凝法制备不同粒度的磁性磨料;在经过镶嵌、研磨、抛光、酸洗之后,采用热场发射扫描电子显微镜(SEM)观察磁性磨料的剖面形貌,结果表明刚玉粉在磁性磨料中的分布具有一定规律,绝大部分刚玉粉均匀牢固致密地嵌于铁磁性基体表层,且嵌入基体的深度大于自身半径,而基体内部基本无刚玉粉颗粒分布,对这一现象产生的原因利用陶瓷颗粒穿透模型和机械作用机制进行系统的计算与分析。     

粘结法制备磁性磨料及其对轴承钢外圆表面的光整加工研究

采用粘结法制备磁性磨料,对磁性磨料制备工艺进行了优化,确定了最终的工艺方案。研究了在磁性磨料粒度及配比不变的情况下,结合剂的种类、结合剂中粘结剂与固化剂的质量比以及混料与结合剂的质量比对轴承钢外圆表面粗糙度的影响。试验结果表明,使用粘结剂为环氧树脂B制备的磁性磨料具有较好的研磨效果,并且当粘结剂与固化剂的质量比为3∶1,以及混料与结合剂的质量比为6∶1时,研磨效果最佳。磁性磨料光整加工技术为轴承钢的表面加工提供了一种新方法。     

磁性磨料的制备

详细介绍了磁性磨料的性能要求和制备方法,同时也阐述了磨粒对研磨效果的影响。     

利用磁力的表面研磨新技术

<正> 利用磁力的研磨技术是近年开发的新技术。以研磨方式分类,可分为干式法和湿式法两类。干式法采用磁性磨料进行研磨,它是保加利亚发明的方法。湿式法是本文作者。所在的研究室发明的方法,这是利用磁性流体的表面研磨技术。1、干式法的表面研磨保加利亚工业试验所发明的利用磁性磨料的表面研磨技术,目前尚不了解其详情。据说是按照下述方法进行研磨:将磁性磨料放置在     

采用粘结法的磁性磨粒制备工艺及实验研究

现有的粘结法制备工艺存在混合不均等问题,且磁介质相和磨粒相在破碎过程中会发生分离,易造成浪费,为此,提出了一种新的粘结法磁性磨粒制备工艺。在相同条件下,运用两种不同工艺分别制备了两种磁性磨粒,并进行了实验研究。采用扫描电镜、三维超景深显微镜观测试件表面,并用电子天平测试试件光整加工前后的质量变化。实验结果表明,采用新粘结法工艺制备的磁性磨粒对试件进行光整加工10 min后,表面粗糙度值Ra从0.800 μm减小到0.076 μm,材料去除率的最大值为0.67 μm/min。与现有粘结法工艺制备的磁性磨粒相比,新粘结法制备的磁性磨粒的微观结构良好、各成分分布均匀,加工性能更加优异。     

磨料有序排布电镀砂轮的制备及其把持力研究

为解决电镀砂轮磨削加工中容屑空间不足的问题，采用点胶微粘接的方法制备了磨料有序排布的电镀砂轮，分析了磨料粘接效果和镀层力学性能。通过SEM分析了磨料/镀层/导电胶的结合界面，并进行了干磨削试验。研究结果表明，直径约为磨料粒径40%的胶点可粘接住磨料，单个胶点上粘接多颗磨料的占比小于6%；双脉冲电镀工艺制备的镀层显微硬度大于500HV，表层残余应力小于100MPa，磨料/镀层/导电胶之间的界面贴合紧密，无明显缺陷；砂轮在磨削时没有出现磨料脱落现象。     

磁性研磨在模具曲面抛光中的应用

针对大型模具曲面精整加工的问题,探讨采用磁性研磨加工模具曲面的工艺。根据磁性研磨加工原理,基于数控铣床研制了磁性研磨实验装置,采用工具旋转的磁性研磨加工方式,磁性磨料受到磁场约束力和离心力的作用,成为影响加工过程正反两方面的因素。对模具曲面进行磁性研磨加工实验,针对模具曲面研磨量不均匀问题,分析了影响曲面研磨量的主要因素,提出了从磁极形状和研磨轨迹等方面控制研磨量的方法。     

New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness(Ra) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid solidification presented can significantly improve the finishing performance and service life of magnetic abrasive, and provide a more practical approach for large-scale industrial production of magnetic abrasive.     

游离磨料线锯切片流体动压效应的数值分析

游离磨料线锯切割技术是目前单晶硅切片的主要加工方法。建立了游离磨料线锯切片过程中流体动压效应的数学模型,并采用有限差分法进行了数值分析,得到了游离磨料线锯切片的流体动压力分布和膜厚。结果表明,当磨粒尺寸较小时,锯丝与晶体间的膜厚大于磨粒尺寸,磨粒悬浮在研磨液中,因此研磨液中磨粒与晶体的碰撞将是材料去除的主要因素。     

磁力光整加工铝镁合金永磁极研究

以主轴改造后的XK7136C数控铣床为平台,以AZ31系镁合金与7075-T651铝合金为研究对象,通过理论计算与磁场仿真,设计出适用于加工铝镁合金结构材料平面的强永磁材料磁极,并采用雾化快凝球形磁性磨粒进行试验,以验证该种光整加工方法的可行性及球形磨粒性能。使用“米字槽”与“田字槽”两种磁极分别对两种材料进行研磨实验。实验结果表明：两种端面开槽方式均可防止磨料的局部堆积,保证磨料的流动性,并使端面磁通密度增大,磁场强度梯度增大,提高研磨效率。两种磁极所研磨表面粗糙度分别为0.126 μm和0.148 μm,端面拥有更大磁通密度的“田字槽”磁极前期研磨效率更佳。     

Improving Electrical Discharge Machined Surfaces Using Magnetic Abrasive Finishing

Abstract

A recast layer is invariably present on surfaces produced by electrical discharge machining (EDM). For some metals with high hardness, the recast layer may contain micro-cracks. This damaged layer can affect the service life of the parts produced by this method. This investigation demonstrates that magnetic abrasive finishing (MAF) process using unbonded magnetic abrasives (UMA), can improve the quality of EDM machined surfaces effectively. The UMA used herein is a mechanical mixture of steel grit and SiC abrasive. SKD11 tool steel was used as the workpiece. Experimental results show that the recast layer and micro-cracks on EDM machined surfaces can be completely removed and a new surface of roughness on the order of 0.04 μm Ra can be produced. Additionally, experiments using the Taguchi method and L₁₈ orthogonal array enable the determination of the optimum process conditions for improving the surface finish. Further, the significance of the control factors was identified with the assistance of analysis of variance (ANOVA), and the optimum combination of the process parameters was verified by conducting several confirmatory experiments.     

Abrasive wear in ultrasonic drilling

Material removal in ultrasonic drilling is caused by the abrasives in the slurry. As a given charge of abrasive circulates, the mean particle size decreases and the initially sharp cutting edges become dull, reducing the machining rate. This paper discusses the mechanism of wear of the abrasive in ultrasonic drilling; the size of abrasives in the working zone governs machining rate, tool wear and production accuracy of the holes drilled     

Improving Electrical Discharge Machined Surfaces Using Magnetic Abrasive Finishing

A recast layer is invariably present on surfaces produced by electrical discharge machining (EDM). For some metals with high hardness, the recast layer may contain micro-cracks. This damaged layer can affect the service life of the parts produced by this method. This investigation demonstrates that magnetic abrasive finishing (MAF) process using unbonded magnetic abrasives (UMA), can improve the quality of EDM machined surfaces effectively. The UMA used herein is a mechanical mixture of steel grit and SiC abrasive. SKD11 tool steel was used as the workpiece. Experimental results show that the recast layer and micro-cracks on EDM machined surfaces can be completely removed and a new surface of roughness on the order of 0.04 μm Ra can be produced. Additionally, experiments using the Taguchi method and L₁₈ orthogonal array enable the determination of the optimum process conditions for improving the surface finish. Further, the significance of the control factors was identified with the assistance of analysis of variance (ANOVA), and the optimum combination of the process parameters was verified by conducting several confirmatory experiments.