表面化学改性法制备非固结磁性磨料工艺与实验研究

发布时间：2018-03-17 18:26

  本文选题：表面化学改性　切入点：磁性磨粒光整加工　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：磁性磨料作为磁性磨粒光整加工技术的磨具,其性能直接影响零件的加工质量、效率及成本,但由于目前的制备工艺难以实现批量制备高性能、低成本的磁性磨料,所以极大地制约了该技术的工业应用。近年来,不少学者采用机械混合法制备了非固结磁性磨料,取得了很好的加工效果。非固结磨料具有许多优点,如制备工艺简单,成本低,磁场作用下形成的“磁刷”刚性较低,能抛光复杂表面等。但目前该方法制备出的磨料存在以下两方面问题:一方面,由于铁磁相、磨粒相与结合剂之间难以形成良好的粘结,在加工过程中,磨粒相易于飞散,影响对工件表面的加工质量和加工效率;另一方面,铁磁相与磨粒相粉末容易在结合剂中发生自身团聚而难以均匀分散,会对工件表面产生划伤等副作用,影响磁性磨料的加工均匀性。针对上述问题,本文提出采用偶联剂对铁磁相和磨粒相表面化学改性,来改善二者在结合剂聚乙烯醇中的相容性和分散稳定性,之后再将改性粉末与聚乙烯醇机械混合均匀来制备非固结磁性磨料。本文主要对偶联剂改性过程中的一些工艺参数进行了实验研究,并对制备的磨料的性能指标进行分析测试。本文的主要研究内容如下:1.分析了非固结磁性磨料光整加工平面原理和材料去除机理,叙述了非固结磁性磨料的组成及性能要求,介绍了加工介质研磨液的分类及作用,重点对单个研磨粒子进行受力分析,得出工件对研磨粒子的法向压力Fpn和铁磁相与磨粒相的粒径比A有关,并推导出A的理论范围。2.制定了非固结磁性磨料的制备工艺流程,以活化指数为表征手段,通过单因素实验研究了改性过程中偶联剂种类、用量、反应温度、反应时间对改性效果的影响。结果表明:在相同实验条件下,钛酸酯偶联剂NDZ-101对还原铁粉和白刚玉的改性效果较好,改性后粉体活化指数较高,疏水性较强,且综合考虑改性效果与经济性,选取最佳用量为3%,最佳反应温度为70℃,反应时间为40min。3.通过磁回路测量装置,测量了非固结磁性磨料的饱和磁感应强度,评价其导磁性能,找出了磁感应强度B达到饱和时磁场强度H和电流I的大小。然后建立现有磁回路装置的三维模型,将非固结磁性磨料简化为球形,采用Maxwell软件对不同电流值下磨料的磁感应强度进行仿真,结果表明实测结果与仿真结果基本一致,测量准确性较高。此外,以SUS304不锈钢板为工件,研究其使用寿命,结果表明:非固结磁性磨料对初始粗糙度Ra为0.4μm左右的304不锈钢板研磨加工,使用寿命较高,大约为36min。4.以加工平板工件为例,检测了非固结磁性磨料的研磨加工性能。通过实验分别探究了偶联剂种类、铁磁相与磨粒相粒径比、研磨液种类及配比、材料性质对表面粗糙度和表面形貌的影响规律。结果表明:非固结磁性磨料加工性能优良,加工后工件表面质量高,达到镜面效果。
[Abstract]:Magnetic abrasive, as the abrasive tool of magnetic abrasive finishing technology, has a direct impact on the quality, efficiency and cost of parts. However, it is difficult to produce high performance and low cost magnetic abrasive in batches. In recent years, many scholars have used mechanical mixing method to prepare unconsolidated magnetic abrasive, which has achieved good processing effect. Unconsolidated abrasive has many advantages, such as simple preparation process. The cost is low, the "magnetic brush" formed by magnetic field is less rigid, and can polish the complex surface. However, the abrasive prepared by this method has the following two problems: on the one hand, because of the ferromagnetic phase, It is difficult to form a good bond between the abrasive phase and the binder. In the process of processing, the abrasive phase is easy to fly away, which affects the processing quality and processing efficiency of the workpiece surface; on the other hand, Ferromagnetic phase and abrasive phase powder are easy to be agglomerated in the binder and difficult to disperse evenly, which will produce side effects such as scratching on the surface of the workpiece and affect the processing uniformity of magnetic abrasive. In this paper, the surface chemical modification of ferromagnetic phase and abrasive phase by coupling agent is proposed to improve their compatibility and dispersion stability in the binder polyvinyl alcohol. Then the modified powder and polyvinyl alcohol were mechanically mixed to prepare unconsolidated magnetic abrasive. In this paper, some technological parameters in the modification process of coupling agent were studied experimentally. The main research contents of this paper are as follows: 1. The plane principle and material removal mechanism of unconsolidated magnetic abrasive finishing are analyzed, and the composition and performance requirements of non-consolidated magnetic abrasive are described. The classification and function of grinding fluid for machining medium are introduced. The stress analysis of single abrasive particle is emphasized. The normal pressure Fpn of workpiece to abrasive particle and ferromagnetic phase are related to particle size ratio A. The theoretical range of A was deduced. 2. The preparation process of unconsolidated magnetic abrasive was established. By means of activation index, the type, amount and reaction temperature of coupling agent in the modification process were studied by single factor experiment. The results showed that the titanate coupling agent NDZ-101 had better modification effect on reduced iron powder and corundum under the same experimental conditions, the activation index of the modified powder was higher, and the hydrophobicity of the modified powder was stronger. Considering the modification effect and economy, the optimum dosage is 3, the optimum reaction temperature is 70 鈩，

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