基于电容耦合的大面积电火花加工方法研究

发布时间：2018-04-08 14:38

本文选题：电火花加工　切入点：电容耦合　出处：《哈尔滨工业大学》2017年硕士论文

【摘要】：在“中国制造2025”的大背景下,我国制造业趋向于精密化、智能化、高效化的方向发展。模具工业是制造业的基础,高精度、寿命长、制造周期短、低成本的模具可大大促进制造业的发展。大面积电火花精加工主要应用于模具制造、航空宇航以及军工产业等行业。在以往的电火花成型加工中,随着加工面积的增大,即使使用很小的电规准,仍然难以获得理想的表面精度。这是由于随着加工面积的增大,工件与电极间的静电容量增大,存储的能量增多,导致放电时该电容存储的能量释放到极间增大放电能量,从而难以获得较小的表面粗糙度。基于电容耦合的大面积电火花加工方法是将脉冲电源与放电极间通过给电电容隔离,与传统的RC张弛式脉冲电源以及独立式晶体管脉冲电源相比,其特点是只有感应电流、无传导电流、避免了分布电容的影响。本文分析了基于电容耦合的大面积电火花加工方法的工作原理;建立了基于电容耦合的大面积电火花加工的仿真模型,并对其充放电特性进行了仿真研究;进行了电容耦合大面积电火花加工方法的三轴精密电火花加工平台的搭建;对基于电容耦合的大面积电火花加工方法的充电特性进行实验研究,实验结果与仿真结果一致,获得了该方法中极间间隙大于并接近放电间隙时脉冲电压幅值与极间间隙之间的关系式;对基于电容耦合的大面积电火花加工方法的放电特性进行了系统深入的实验研究,观测了该方法放电过程的一般放电波形,分析了该方法中极间间隙远大于放电间隙的脉冲电压幅值、给电电容、脉冲频率、给电方式、加工面积对放电的影响;观测并分析了基于电容耦合的大面积电火花加工中的实验现象,对该方法的加工特性进行实验研究和理论分析,明确了流场条件、脉冲宽度、放电极性对积碳现象以及放电的影响;观测并分析了持续加工中的放电状态的变化规律;提出了基于电容耦合的大面积电火花加工方法的两种减小放电能量的途径,并对两种方法的实验设备及工艺需求进行了分析;利用基于电容耦合的大面积电火花加工方法在直径为100mm的SKD61模具钢表面进行加工得到Ra0.3~0.5μm的表面粗糙度。
[Abstract]:Under the background of "made in China 2025", China's manufacturing industry tends to develop in the direction of precision, intelligence and high efficiency.Mould industry is the foundation of manufacturing industry. The mould with high precision, long life, short manufacturing period and low cost can greatly promote the development of manufacturing industry.Large-area EDM is mainly used in die manufacturing, aerospace industry and military industry.In the past EDM, with the increase of machining area, it is still difficult to obtain the ideal surface precision even if small electrical gauge is used.This is because the electrostatic capacity between the workpiece and the electrode increases and the energy stored increases with the increase of the machining area, which results in the discharge of the energy released by the capacitor to increase the discharge energy between the electrodes, and it is difficult to obtain a smaller surface roughness.The method of large area EDM based on capacitive coupling is to isolate the pulse power supply from the discharge electrode by electric capacitance. Compared with the traditional RC Zhang Chi pulse power supply and the independent transistor pulse power supply, the characteristics of the EDM method are only inductive current.No conduction current, to avoid the effect of distributed capacitance.In this paper, the working principle of large area EDM based on capacitive coupling is analyzed, the simulation model of EDM based on capacitive coupling is established, and the charge-discharge characteristics of EDM are simulated.The three-axis precision EDM platform of capacitance-coupled large-area EDM is built, and the charging characteristics of the capacitance-coupled large-area EDM are studied experimentally, and the experimental results are consistent with the simulation results.The relationship between the pulse voltage amplitude and the gap between the electrodes is obtained when the gap between the electrodes is larger than or close to the discharge gap, and the discharge characteristics of the large area EDM method based on capacitive coupling are studied systematically and experimentally.The general discharge waveforms of the discharge process are observed, and the effects of the pulse voltage amplitude, the electric capacitance, the pulse frequency, the power supply mode and the machining area on the discharge in the method are analyzed, in which the gap between the poles is far larger than the discharge gap.The experimental phenomena in large area EDM based on capacitive coupling are observed and analyzed. The processing characteristics of this method are studied experimentally and theoretically, and the flow field conditions and pulse width are determined.The effect of discharge polarity on carbon deposition and discharge; observing and analyzing the change of discharge state in continuous machining; proposing two ways to reduce discharge energy based on capacitive coupling method of large area EDM.The experimental equipment and process requirements of the two methods are analyzed, and the surface roughness of Ra0.3~0.5 渭 m is obtained by using the large area EDM method based on capacitive coupling on the surface of SKD61 die steel with diameter 100mm.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG661

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