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R. Rajeswari 《Machining Science and Technology》2020,24(2):245-273
AbstractDie-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. Finish EDM conditions are often selected to produce good quality surfaces. Attempts to enhance the finishing capabilities using ultrasonic vibration and powder-added dielectric medium have been reported in the literature. However, the changes in the gap phenomena with ultrasonic assistance and powder addition have not been analyzed. In this article, finish EDM of hardened D3 steel has been carried out based on full factorial design of experiment with three levels of setting voltage, setting current and pulse on time. The performance of ultrasonic assisted and graphite powder-added EDM are evaluated by analyzing the voltage and current pulse trains in finishing operation for the first time. Based on two new parameters, namely energy expended over a second (E) and ratio of energy due to sparks in relation to total discharge energy (PF), the results are discussed and also compared with those obtained with conventional EDM for selected conditions. Even though E of 102.9 J (PF?=?0.862) with ultrasonic vibration is higher than E of 43.0 J (PF?=?1.0) with powder mix, the molten metal is removed effectively from the gap by ultrasonic vibration which results in a relatively better surface. The micrographs of cross-section and surface of the workpieces obtained using optical and scanning electron microscopes, respectively, also reveal their relative performance. 相似文献
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Ching-Tien Lin Han-Ming Chow Lieh-Dai Yang Yuan-Feng Chen 《The International Journal of Advanced Manufacturing Technology》2007,34(1-2):104-110
This study addresses micro-slit EDM machining feasibility using pure water as the dielectric fluid. Experimental results revealed
that pure water could be used as a dielectric fluid and adopting negative polarity EDM machining could obtain high material
removal rate (MRR), low electrode wear, small slit expansion, and little machined burr, compared to positive polarity machining.
In comparing kerosene versus pure water, pure water was observed to cause low carbon adherence to the electrode surface. Also
discharge energy does not decrease and the discharge processes are not interrupted. Therefore, MRR was higher, and related
electrode wear ratio compared to kerosene use was lower. In a continual EDM with multi-slit machining, kerosene will cause
carbon element adherence, creating an initially high MRR and electrode wear, with rapid decline. However, pure water will
not cause carbon element adherence on the electrode surface, so MRR and electrode wear is always stable in this process. 相似文献
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研制了一种超声-放电复合加工参数选择专家系统,介绍了如何结合应用该专家系统与机床实时控制系统,并作了实际加工试验。 相似文献
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混粉电火花加工中粉末对工件表面的影响 总被引:1,自引:1,他引:1
对不同加工条件下混粉电火花加工后工件表面的硅含量进行了对比测量。实验结果表明:当峰值电流小于4A时,混粉电火花加工后的工件表面硅含量随峰值电流的增大而急剧减小,而当峰值电流大于4A时,工件表面硅含量随峰值电流的增大而缓慢增加;混粉电火花加工后的工件表面硅含量随脉宽的增大而增加;在其他加工条件相同的情况下,对于相同的单次放电脉冲能量,混粉电火花加工获得的工件表面硅含量随峰值电流变化的关系呈近似二次曲线。引入熵的概念,对产生上述结论的原因进行了分析,并解释了混粉电火花加工可以改善工件表面质量的机理。 相似文献
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Biing Hwa Yan Kun Ling Wu Fuang Yuan Huang Chun Chieh Hsu 《The International Journal of Advanced Manufacturing Technology》2007,34(1-2):96-103
In order to achieve a mirror-like workpiece surface by EDM, a micro-energy EDM or a manual lapping is normally used. However,
both methods are time consuming and economically unattractive. To have better performance, a sinking EDM machine was first
used in this research on SKD 61 for a micro-energy discharge process followed by the electrophoretic deposition (EPD) process
to coat Al2O3 particles uniformly on a rotation electrode. The precision polishing process was then applied on the discharged workpiece
with suitable parameters including the voltage, electrode rotating speed, pH value of electrolyte, and abrasive concentration.
After the EDM process, the surface roughness and the recast layer thickness of a workpiece could also be reduced. The experimental
data showed that when 0.3 μm of Al2O3 particles was used for the EPD polishing process, the initial roughness of a discharge surface could be improved from 0.52 μm
Ra (6.50 μm Rt) to a mirror-like surface of 0.068 μm Ra (0.742 μm Rt). Also, the total working time could be reduced significantly
to within the range of 5 to 10 min. 相似文献
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根据电火花加工工艺特点 ,建立基于遗传算法的加工过程人工神经网络模型 ,实现加工结果的预测。根据预测结果 ,在保证表面粗糙度要求的前提下 ,以最大加工速度为目标 ,用遗传算法实现加工参数的优化。实验结果表明以上算法可有效解决电火花加工条件优化的问题 ,自动生成加工参数 ,而且收敛速度较快 ,满足机床控制的要求。 相似文献
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Minggang Xu Zhiwei Wu Feng Gao Linlin Liu Enyu Song 《Journal of Mechanical Science and Technology》2020,34(7):2751-2760
Rotating ultrasonic vibration assisted EDM is a composite machining method that uses EDM to etch a metal surface and adds rotating and ultrasonic vibration 相似文献
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This paper proposes two new methods to observe discharge phenomena without interference from the plasma in electrical discharge machining. The first method uses a bandpass filter with a bandwidth of 800–820 nm and laser illumination with a wavelength of 800–820 nm. The second method also uses a bandpass filter with a bandwidth of 800–820 nm; however, in this method, the tungsten material is used not only as the tool electrode but also as the illumination source. First, the discharge process was observed using traditional methods to investigate the influence of the plasma on the observation of the discharge process. Then, the process of removing molten material from both the tool electrode and workpiece, as well as molten pool movement, was observed using the first method proposed in this paper. The material removed from the tool electrode was scattered upward along the end profile of the tool electrode, while the material removed from the workpiece was distributed along the horizontal direction. To explain these phenomena, the flow distribution in the gap was qualitatively analyzed using a fluid simulation. Finally, the discharge process was also observed using the second method proposed in this paper. A tungsten tool electrode can emit light with a wavelength of 800–820 nm, which shines on the observed region during the discharge process. The observation results verified the phenomenon of multiple explosions of the molten pool during the discharge process. Moreover, it was found that the material removed by the explosion of the molten pool was scattered in different directions and hardly influenced by the flow distribution in the gap. 相似文献
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A new technique of EDM coring of single crystal silicon carbide (SiC) ingot was proposed in this paper. Currently single crystal SiC devices are still of high cost due to the high cost of bulk crystal SiC material and the difficulty in the fabrication process of SiC. In the manufacturing process of SiC ingot/wafer, localized cracks or defects occasionally occur due to thermal or mechanical causes resulted from fabrication processes which may waste the whole piece of material. To save the part of ingot without defects and maximize the material utilization, the authors proposed EDM coring method to cut out a no defect ingot from a larger diameter ingot which has localized defects. A special experimental setup was developed for EDM coring of SiC ingot in this study and its feasibility and machining performance were investigated. Meanwhile, in order to improve the machining rate, a novel multi-discharge EDM coring method by electrostatic induction feeding was established, which can realize multiple discharges in single pulse duration. Experimental results make it clear that EDM coring of SiC ingot can be carried out stably using the developed experimental setup. Taking advantage of the newly developed multi-discharge EDM method, both the machining speed and surface integrity can be improved. 相似文献
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