【作者】 贺新升；

【导师】 张雷；

【作者基本信息】 吉林大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 精密模具制造,工件表面的精整加工都是制造业的难题,是我国制造业发展必须突破的瓶颈。而这些问题的解决,都需要先进研抛技术的支持。本文研究了电流变抛光技术,主要用于解决非球面透镜及其硬质合金模具的精整加工问题。电流变抛光技术作为一种新兴的抛光技术,适用于加工表面形状复杂的非球面光学元件及难以加工的硬质合金模具。由于它适用面广,加工成本低,也可用于常规工件的加工,具有很高的实用价值。电流变抛光是一种新颖的抛光方法,但目前尚处于实验室研究阶段。本文主要在抛光工具,抛光设备方面做出了一些创新,建立了材料去除模型,做了大量的验证实验。本文研制了五轴电流变抛光设备,可以完成包括非球面在内各种常见面型的抛光作业。本文发明了一种新型抛光工具—集成电极工具,在抛光对象、抛光效率、使用方便性等方面比尖锥状工具都有很大的提高。文中研究了集成电极工具的抛光机理,计算了集成电极端部的电场分布,建立了电流变抛光的材料去除模型。指出电压、磨料浓度、抛光时间及主轴转速是影响去除深度的几大因素。通过实验,得到了各因素与去除深度的关系。在五轴电流变抛光设备上进行了一系列抛光实验。在抛光的适用性及工艺方面进行了较为全面的实验研究,从不同角度验证了电流变抛光是有发展前途的一种新的光整加工手段。课题研究工作得到了教育部新世纪优秀人才资助计划、吉林省杰出青年基金项目(20050121)及特种装备制造与先进加工技术教育部重点实验室开放基金资助项目(2009EP006)的支持。更多还原

【Abstract】 Precision mold manufacturing and surface finishing processing of the workpiece are bottleneck that China’s manufacturing industry must break through. In order to resolve these problems, we need some advanced polishing technology. This paper studies the ER fluid-assisted polishing technology that mainly be used to polish non-spherical lens and cemented carbide dies.Based on the research results of home and abroad, this paper analyzes the current study status of ER fluid-assisted polishing technology. This paper has made a number of innovative works mainly in the polishing equipment, polishing tool, the remove theory of polishing technology, etc. This project is supported by“Combined with the Ministry of Education New Century Excellent Talents Scheme”and“the Outstanding Youth Fund of Jilin Province”.The five-axis ER fluid-assisted polishing equipment, which has three linear axes and two rotary axes, is developed in this paper. It has high positioning accuracy to meet demand for polishing workpiece with free-form surface. Inverse kinematic model of the system has been established in this paper. On the case of known cutter location data, the amount of movement in each axis of the ER fluid-assisted polishing equipment can be calculated. Cutter location data come from CAM software or calculation. The experiment of polishing the Non-spherical parts was done in this paper. The experimental results show that the actual trajectory and the ideal trajectory fitting, so the inverse kinematics model is right. Using VB language, this paper has developed user program of ER fluid-assisted polishing equipment. It has capabilities of manual control, automatic control, 3D trajectory display. Some experiments for polishing different face parts show that the device, which can polish the most common face, including free-form surfaces, has high practical value.The control systems of ER fluid-assisted polishing equipment require of fast response, good stability and high positioning accuracy. This paper has developed a dual-mode closed-loop control system based on error compensation. In the control system, using the U.S. Delta Tau’s PMAC card as controller. Three linear axes using high-precision AC servo motor-driven, two axis of rotation constituted by electric rotary tables. Using a high-precision grating ruler and the encoder feedback position information about each axes, constitutes a closed-loop control system. The principle of dual-mode control based on error compensation as follows. Firstly, using laser interferometer, detect grating ruler and screw obtain pitch error compensation tables in a state of semi-closed-loop calibration. The position control has two phases of the sub-rough control and precise control. In the rough control stage, screw run in a state of semi-closed-loop calibration until the position where after the error compensation value set. At this time amend error compensation table. Next is the precise control stage. The whole closed-loop control strategy is the self-adaptive fuzzy PID control. Paper positioning accuracy of the control system was tested. Experiment proved that each axis of the device positioning accuracy within 5 microns. The device can meet the needs of ER polished and it was explored a new path for improve the positioning accuracy of conventional equipment.Polishing tool is the core component of the device and has a great influence on the polishing efficiency. This paper has developed two new types of ER fluid-assisted polishing tools -integrated electrode tool. One is parallel plate electrodes tool, the other is ring-like integrated electrodes tool. Two types of integrated electrode tool polish workpiece with Polishing Head generated by the ER effect. So it can polish not only conductor but also non-conductive workpiece. while polishing workpiece, the integrated electrode tool do not need to add auxiliary electrode so is can polish the most common face, including free-form surfaces. The differences of two types of integrated electrode tool mainly reflect differences in their electric field distribution. This paper has calculating the electric field intensity distribution of the integrated electrode tool. The calculating results show that the electric field strength was saddle-shaped distribution outer ends of the parallel plate integrated electrodes tool. It is the largest close to the plate and it is smaller at center and both sides of. With the same terminal voltage, different gap parallel-plate integrated electrodes tool form a flexible polishing heads are 12mm in length. The calculating results take a guide for making the parallel-plate integrated electrodes tool. With same of the terminal voltage and polishing gap, ER fluid-assisted polishing tool with the smaller plate spacing has even higher electric field strength, a better polishing efficiency. Polish efficiency and reduce the positioning accuracy of polishing take into account, polishing suitable gap to no more than 1mm. The electric field strength of outer ends of circular ring-like polishing tools is circular ring-like distribution. It is decreasing in the direction of radius. Location centered on the largest electric field strength.This paper has established material removal model of ER fluid-assisted polishing. Polishing pressure is equal to the yield stress. With the Preston equation, this paper established the material removal rate model. Some material removal experiments of ER fluid-assisted polishing the cemented carbide and other metal materials has been done in this paper. The experiments results show that distribution of the removal depth and the theoretical model fitting. It is prove that the material removal model is right. This paper pointed out that the voltage, concentration of abrasive, polishing time and speed affect the removal depth of several factors. Through some experiments, the relationship various factors with the removal depth were obtained. This paper explored the mechanism of ER fluid-assisted polishing with some experiments. Through orthogonal experiment, this paper has obtained the optimal combination of various factors. Experimental results show that, on the case of using self-prepared ER fluid polishing optical glass specimen, the parameter combinations of the voltage of 2500V, spindle speed 4000r/min, polishing time of 10min, abrasive concentration of 15% has the best polish effect. Some polishing experiments about single-factor, different materials, different face, different abrasive are done in this paper. Experimental results show that the surface roughness Ra values and each parameter are inversely proportional. When the voltage or the concentration of abrasives is too large, the surface of workpiece will be damaged. Polishing carbide materials, diamond abrasive is required. The integrated electrode tool can polish different face. If raised the dwell time, it will get a better polishing effect. Silicon carbide abrasive is the best choice in three kinds of artifacts alumina, diamond, silicon carbide while the polishing of optical glass. A large number of experiments show that ER fluid-assisted polishing is promising a new finishing technology.更多还原