【作者】 邢满禧；

【导师】 孙桓五；

【作者基本信息】 太原理工大学 ， 机械设计及理论， 2008， 硕士

【摘要】 液体磁性磨具是应用磁致相变原理研制的一种新型精密光整加工用磨具,在无外加磁场时,该磨具呈标准的牛顿流体,可以和工件充分接触。而在施加磁场之后,该磨具的表观粘度和剪切屈服应力增加几个数量级以上,由牛顿流体迅速相变为类固体,而且这种变化是连续的、可逆的,一旦去掉外部磁场,又恢复为牛顿流体。液体磁性磨具的这种独特的流变特性,使液体磁性磨具类似于一个“柔性”砂轮,能够与各种型面的零件很好地贴合在一起,当磨具和工件有相对运动时就可以实现对工件的光整加工。本文在目前液体磁性磨具已有研究的基础上,采用理论分析、数值模拟相结合的方法对液体磁性磨具及其光整加工进行了系统的研究:首先简要的介绍了液体磁性磨具的概念、组成、物理性质、微观流变机理,以及液体磁性磨具光整加工的机理、材料去除模型、实验装置、工艺参数等相关基本理论,然后归纳总结了现有液体磁性磨具的微观和宏观剪切应力模型;利用临界雷诺数法确定了光整加工中液体磁性磨具的流动状态,在流动状态确定的基础上,利用非牛顿流体力学和张量分析的理论并结合双粘度模型,建立了液体磁性磨具光整加工的流体动力学模型,明确了光整加工中液体磁性磨具运动学和动力学特性,得到了液体磁性磨具的剪切应力和速度场分布;接着讨论确定了液体磁性磨具的分析区域,并借助有限元分析软件-ANSYS,分析和比较了施加磁场前后的液体磁性磨具的剪切应力和速度场;最后对全文进行了总结,并提出了分析中出现的问题和不足,同时展望了下一步的研究工作。更多还原

【Abstract】 Fluid magnetic abrasives (FMA) are a new kind of precision finishing abrasives, which take advantage of the theory that the magnetism induces phase to change,in the absence of an applied magnetic field,FMA exhibit Newtonian-like behaviour ,can contact workpiece sufficiently. When exposed to a magnetic field ,the viscosity and yield shearing stress increases several orders of magnitude ,the FMA change from Newtonian fluid to solid,and this change is successive、reversible,in case of removing external magnetic field ,the FMA return to Newtonian fluid. The unique reheolgical property of the FMA makes it like a "soft" grinding wheel,can adapt to different profile of workpiece ,when there is relative movement between the FMA and workpiece,finishing is realized.The dissertation ,which is based on the existing study of the FMA,research into the FMA and its finishing systematicly with adopting combination of theoretical analysis and numerical simulation: first of all,the dissertation introduce concept、composition、physical properly、microcosmic rheological mechanism of the FMA,and also the correlative basic theory of FMA finishing mechanism、material removed model、experimental equipment、technical parameters,then sum up the existing microcosmic and macroscopical shearing stress model of the FMA, confirm flow state of the FMA during finishing with adopting critical Renault method,based on the confirmation of the flow state,establish hydrokinetics model of the FMA finishing with adopting the theory of non-newtonian liquid and tensor analysis and combining with biviscosity model,confirm kinematics and mechanics property of the FMA finishing,gained shearing stress and velocity field distributing of the FMA,then discuss and confirm analysis area of the FMA, analyse and compare with shearing stress and velocity field of the FMA, when in absence of and exposed to external magnetic field ,by virtue of finite element analysis software -ANSYS;finally,sum up the whole article,and present problem and deficiency during analysis,and bring forward next investigation work simultaneously.更多还原