绝缘硬脆材料电化学放电加工关键技术研究
发布时间：2018-11-22 08:33
【摘要】：绝缘硬脆材料具有绝缘性好、耐腐蚀、耐高温、硬度高等特点,目前在航空航天、生物医学、化工、冶金等领域受到广泛应用。由于其本身的高硬度和高脆性特点,传统的机械切削加工方法难以完成微细结构的加工,电化学放电加工方法是目前较为合适的一种加工方法。本文针对绝缘硬脆材料微细结构的加工技术,开展了电化学放电加工方法的研究。本文首先分析了电化学放电加工机理,详细阐述其加工过程和材料去除原理,总结了目前常规电化学放电加工方法存在的问题:随着加工孔深度的增加,工具电极端部工作液更新困难,气膜难以形成,放电集中在入口处,导致入口直径过大,加工速度和加工质量降低。针对这些问题,提出了倒置电化学放电加工方法,采用工件在上工具电极在下的布局形式,利于形成稳定气膜,维持该区域放电加工;工具电极的旋转运动利于工作液更新以及加工屑的排出。在此基础上,搭建了倒置电化学放电加工平台。利用搭建的倒置加工平台,开展微小孔的加工工艺实验,并与常规正置加工方法进行了对比实验。通过采集加工中的电流信号,分析了倒置加工特性;分析了加工电压、工作液浓度、进给速度、旋转运动等参数对倒置加工的影响,对比了两种加工方法加工的孔的入口直径、加工深度、孔的锥度和加工重复性等指标。实验结果表明,倒置旋转加工方法能够促进工具电极端部工作液更新,形成稳定气膜,减少孔入口处的放电,从而提高加工速度和加工重复性,减小入口直径和锥度。针对微晶云母陶瓷上的拉瓦尔喷管加工,设计了合理的工艺流程,应用电化学放电加工方法,进行微孔加工实验研究。实验中采用螺旋工具电极,进一步提高孔内工作液循环,维持工具电极端部放电,减小了入口直径,提高了加工速度,加工出符合要求的通孔。设计了超声加工平台,加工出拉瓦尔喷管。上述研究结果表明,本文提出的倒置电化学放电加工方法,在非导电材料的微细结构加工中有很大的潜力,值得进一步深入研究。
[Abstract]:Hard and brittle insulating materials are widely used in aerospace, biomedical, chemical, metallurgical and other fields because of their good insulation, corrosion resistance, high temperature resistance and high hardness. Because of its high hardness and high brittleness, the traditional machining method is difficult to finish the micro-structure machining. Electrochemical discharge machining is a more suitable machining method. In this paper, electrochemical discharge machining (EDM) has been carried out on the micro structure of hard and brittle insulating materials. In this paper, the mechanism of electrochemical discharge machining is analyzed, the machining process and material removal principle are described in detail, and the existing problems of conventional electrochemical discharge machining methods are summarized: with the increase of hole depth, The working fluid of the electric extreme part of the tool is difficult to renew, the gas film is difficult to form, and the discharge is concentrated at the entrance, which leads to the excessive diameter of the inlet and the decrease of the machining speed and quality. Aiming at these problems, an inverted electrochemical discharge machining method is put forward, which adopts the layout of the top tool electrode in the workpiece, which is conducive to the formation of stable gas film and the maintenance of the discharge machining in this area. The rotating movement of the tool electrode is beneficial to the renewal of working fluid and the discharge of machining chips. On this basis, an inverted electrochemical discharge machining platform was built. Using the inverted machining platform, the machining process experiment of micro hole is carried out, and the contrast experiment is carried out with the conventional positive machining method. The characteristics of inverted machining are analyzed by collecting the current signal in machining. The effects of the parameters such as voltage, working fluid concentration, feed speed and rotation motion on the inverted machining are analyzed. The inlet diameter, machining depth, hole taper and processing repeatability of the two machining methods are compared. The experimental results show that the inverted rotating machining method can promote the working fluid renewal of the electric extreme part of the tool, form a stable gas film, reduce the discharge at the entrance of the hole, improve the machining speed and repeatability, and reduce the inlet diameter and taper. Aiming at the processing of Laval nozzle on microcrystalline mica ceramics, a reasonable technological process was designed, and the experimental study of micropore machining was carried out by using electrochemical discharge machining method. The spiral tool electrode is used in the experiment to further improve the working liquid circulation in the hole, to maintain the electric extreme discharge of the tool, to reduce the inlet diameter, to increase the machining speed and to produce the through hole that meets the requirements. The ultrasonic machining platform is designed and the Laval nozzle is machined. The results show that the inverted electrochemical discharge machining method proposed in this paper has great potential in the fabrication of non-conductive materials, and it is worthy of further study.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG662
[Abstract]:Hard and brittle insulating materials are widely used in aerospace, biomedical, chemical, metallurgical and other fields because of their good insulation, corrosion resistance, high temperature resistance and high hardness. Because of its high hardness and high brittleness, the traditional machining method is difficult to finish the micro-structure machining. Electrochemical discharge machining is a more suitable machining method. In this paper, electrochemical discharge machining (EDM) has been carried out on the micro structure of hard and brittle insulating materials. In this paper, the mechanism of electrochemical discharge machining is analyzed, the machining process and material removal principle are described in detail, and the existing problems of conventional electrochemical discharge machining methods are summarized: with the increase of hole depth, The working fluid of the electric extreme part of the tool is difficult to renew, the gas film is difficult to form, and the discharge is concentrated at the entrance, which leads to the excessive diameter of the inlet and the decrease of the machining speed and quality. Aiming at these problems, an inverted electrochemical discharge machining method is put forward, which adopts the layout of the top tool electrode in the workpiece, which is conducive to the formation of stable gas film and the maintenance of the discharge machining in this area. The rotating movement of the tool electrode is beneficial to the renewal of working fluid and the discharge of machining chips. On this basis, an inverted electrochemical discharge machining platform was built. Using the inverted machining platform, the machining process experiment of micro hole is carried out, and the contrast experiment is carried out with the conventional positive machining method. The characteristics of inverted machining are analyzed by collecting the current signal in machining. The effects of the parameters such as voltage, working fluid concentration, feed speed and rotation motion on the inverted machining are analyzed. The inlet diameter, machining depth, hole taper and processing repeatability of the two machining methods are compared. The experimental results show that the inverted rotating machining method can promote the working fluid renewal of the electric extreme part of the tool, form a stable gas film, reduce the discharge at the entrance of the hole, improve the machining speed and repeatability, and reduce the inlet diameter and taper. Aiming at the processing of Laval nozzle on microcrystalline mica ceramics, a reasonable technological process was designed, and the experimental study of micropore machining was carried out by using electrochemical discharge machining method. The spiral tool electrode is used in the experiment to further improve the working liquid circulation in the hole, to maintain the electric extreme discharge of the tool, to reduce the inlet diameter, to increase the machining speed and to produce the through hole that meets the requirements. The ultrasonic machining platform is designed and the Laval nozzle is machined. The results show that the inverted electrochemical discharge machining method proposed in this paper has great potential in the fabrication of non-conductive materials, and it is worthy of further study.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG662
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