电流变液辅助精细加工机理研究

【作者】 毕非凡；

【导师】 阎秋生；

【作者基本信息】 广东工业大学 ， 机械制造及其自动化， 2005， 硕士

【摘要】 粒子分散型电流变液(Electrorheological Fluid,简称ER液体)是一种功能型液体材料,是具有较高介电常数的分散颗粒分散于具有较低介电常数的绝缘液体中形成的一类均匀悬浮液。它具有由电场强度可以控制其粘度的特性,在外加电场作用下电流变液中的固体粒子会产生类似半导体材料的极化现象,相互吸引,形成沿电场方向首尾相接的粒子链,当电场强度增大到一定程度时出现“固化”现象,利用电流变液的电控力学行为,可以方便地实现高效率的机-电能量转换。 本研究课题利用电流变液在电场作用下粘变固化的电流变效应将磨料微粒混入电流变液体之中,电流变分散颗粒的成链分布约束磨料微粒形成微小直径砂轮,用于微细加工过程。即以锥状工具作为外加电场阴极,在工件加工表面设置电场阳极,形成的电力线一端将聚集于工具尖端而另一端呈辐射状,电流变液中产生的链状结构将微细磨料固定于这些链状结构中,此时在工具尖端形成一个由磨粒球团构成的呈辐射状的微小砂轮,当工具尖端旋转时,磨粒随之运动产生微磨削作用。在加工过程中,通过改变外加电压等电参数和电流变液组分、体积比等物理特性、加工时间以及锥状工具电极与工件的距离等参数来控制动态微小直径砂轮的尺寸大小、刚度、磨粒相互结合强度等以获得理想的加工效果。 实验通过光学显微镜和扫描电子显微镜观察分析试件已加工表面的特征,发现研磨过程中工件材料存在三种去除模式:脆性断裂、塑性去除以及脆塑共存方式,初步弄清了工件材料去除模式与电流变液动态微小砂轮的尺寸和刚度之间的对应关系,试图通过优化控制加工过程相关的电参数与物理参数来得到理想的材料去除模式而获得完整的加工表面。 利用粒子分散型电流变液作为即效砂轮结合剂,将混入电流变液中的磨料微粒约束和团聚在一起形成动态微小直径砂轮,用于研磨光学玻璃,改变传统固结磨料研磨工具所受的尺寸限制,可满足微器件毫米亚毫米尺寸微细结构的加工的要求,是与微机械微装置发展需求相适应的微细加工新工艺方法。更多还原

【Abstract】 Particle-dispersed Electrorheological-fluid (ER fluid) is a type of foundational fluid material. The fluid is made from uniform suspensions of an insulating base fluid with lower dielectric constants and particles with high dielectric constants. It has an especial characteristic that its viscosity can be dramatically controlled by external electric field. Following the applied electric field, the ER particles become polarized, such as semiconductor material, rapidly aggregate into fibrous columns. When the external electric field reaches a certain voltage ER fluid will be transited from a fluid state to a solid-like state. So it is convenient to realize energy transformation efficiently by utilizing such electric-controlled characteristic of ER fluid.In our research, particle-dispersed ER fluid is used as a special instantaneous bond to cohere abrasive particles in the ER fluid so as to form dynamical tiny grinding wheel in grinding for fine machining. Thus, when abrasive particles is put into the ER fluid and electric power is supplied such that the needle-like tool is cathode and the workpiece is anode, one end of the electric force lines will converge on the tip of the tool and the other end of the electric force lines will be an emissive shape. The abrasive particles are banded in the ER particles and this time a tiny wheel is formed. By regulating some parameters such as voltage, ingredient, volume rate of ER fluid, machining time, as well as distance between cone-tool and workpiece etc, the size, rigidity, and abrasive mutual combine-intensity of the micro grinding wheel can be controlled in order to achieve an expected machining effect.Experiments have been carried out by using optical-microscope and SEM to analyze the characteristics of processed workpiece surface and discover three material removal modes: fragile mode, plastic removal mode and both coexistence mode. Based on the experiments, relationship between material removal modes and the size, intensity of dynamic tiny grinding wheel is presented in this paper to obtain ideal material removal mode for the sake of achieving perfect machining surface by controlling correlative electrics parameters and physics parameters.更多还原