共查询到20条相似文献,搜索用时 15 毫秒
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Ultrasonic vibration was applied to dielectric fluid by a probe-type vibrator to assist micro electrical discharge machining of deep micro-holes in ceramic materials. Changes of machined hole depth, hole geometry, surface topography, machining stability and tool material deposition under various machining conditions were investigated. Results show that ultrasonic vibration not only induces stirring effect, but also causes cloud cavitation effect which is helpful for removing debris and preventing tool material deposition on machined surface. The machining characteristics are strongly affected by the vibration amplitude, and the best machining performance is obtained when carbon nanofibers are added into the vibrated dielectric fluid. As test pieces, micro-holes having 10 μm level diameters and high aspect ratios (>20) were successfully fabricated on reaction-bonded silicon carbide in a few minutes. The hybrid EDM process combining ultrasonic cavitation and carbon nanofiber addition is demonstrated to be useful for fabricating microstructures on hard brittle ceramic materials. 相似文献
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Q.H. Zhang R. Du J.H. Zhang Q.B. Zhang 《International Journal of Machine Tools and Manufacture》2006,46(12-13):1582-1588
This study focuses on using ultrasonic to improve the efficiency in electrical discharge machining (EDM) in gas medium. The new method is referred to as ultrasonic-assisted electrical discharge machining (UEDM). In the process of UEDM in gas, the tool electrode is a thin-walled pipe, the high-pressure gas medium is applied from inside, and the ultrasonic actuation is applied onto the workpiece. In our experiment, the workpiece material is AISI 1045 steel and the electrode material is copper. The experiment results indicate that (a) the Material Removal Rate (MRR) is increased with respect to the increase of the open voltage, the pulse duration, the amplitude of ultrasonic actuation, the discharge current, and the decrease of the wall thickness of electrode pipe; and (b) the surface roughness is increased with respect to the increase of the open voltage, the pulse duration, and the discharge current. Based on experimental results, a theoretical model to estimate the MRR and the surface roughness is developed. 相似文献
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超声-电火花复合加工参数的选择及合理搭配对加工方法的应用、生产率的提高和工具电极的损耗都极其重要,是稳定高效加工进行的前提和保证。通过分析复合加工的主要影响因素,建立了基于BP人工神经网络的超声电火花加工工艺参数优化系统和相应的数据库系统。在给定条件下,系统得到的加工参数更加趋于合理,复合加工系统的总体性能得到提高,克服了传统单纯依赖于工艺数据库的参数选取系统的局限性。试验结果与预测结果有较好的一致性,表明了该系统可为超声电火花加工提供合理可靠的加工方案,系统更加便于用户操作。 相似文献
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简述了电火花加工、超声放电复合加工技术的原理及特点;重点对超声振动辅助气中放电加工的原理和工艺规律进行了深入的探讨,并从试验结果分析中得出了该技术特有的基本工艺规律. 相似文献
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Jianguo Zhang Norikazu Suzuki Yilong Wang Eiji Shamoto 《Journal of Materials Processing Technology》2014,214(11):2644-2659
This paper presents essential investigations on the feasibility of ductile mode machining of sintered tungsten carbide assisted by ultrasonic elliptical vibration cutting technology. It lays out the foundations toward efficient application of elliptical vibration cutting technology on tungsten carbide. Tungsten carbide is a crucial material for glass molding in the optics manufacturing industry. Its grain size and binder material have significant influence not only on the mechanical and chemical properties but also on the machining performance of tungsten carbide. In order to investigate the influence of material composition on tungsten carbide machining, a series of grooving and planing experiments were conducted utilizing single crystal diamond tools. The experimental results indicated that as compared to ordinary cutting where finished surface deteriorates seriously, ductile mode machining can be attained successfully by applying the elliptical vibration cutting technique. It was also clarified that the binder material, the grain size, cutting/vibration conditions as well as crystal orientation of the diamond tool have significant influence on the tool life and the machined surface quality. Based on these fundamental results, feasibility of micro/nano-scale fabrication on tungsten carbide is investigated. By applying amplitude control sculpturing method, where depth of cut is arbitrary changed by controlling the vibration amplitude while machining, ultra-precision textured grooves and a dimple pattern were successfully sculptured on tungsten carbide in ductile mode. 相似文献
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Cheng-Kuang Yang Chih-Ping Cheng Chao-Chuang Mai A. Cheng Wang Jung-Chou Hung Biing-Hwa Yan 《International Journal of Machine Tools and Manufacture》2010,50(12):1088-1096
Electrochemical discharge machining (ECDM) is an emerging non-traditional machining process that involves high-temperature melting assisted by accelerated chemical etching. In this study, the tool electrode (200 μm in diameter) is fabricated by wire electrical discharge grinding (WEDG). After the tool electrode is machined, the surface roughness of tool electrode materials (stainless steel, tungsten carbide, and tungsten) is different because of the physical properties. However, the surface roughness affects the wettability on tool electrode, and also changed the coalesce status of gas film in ECDM. Hence, this study explores the wettability and machining characteristics of different tool electrode materials and their impact on gas film formation. Their machining performance and extent of wear under gravity-feed micro-hole drilling are also examined. Experimental results show that the optimal voltage of different tool electrode can shed light on the machining performance. Moreover, wettability of tool electrode is determined by surface roughness of tool material, which in turn affects the coalesce status of gas film, machining stability and micro-hole diameter achieved. In addition, differences in tool material also results in variations in machining speed. Significant tool wear is observed after repeated gravity-feed machining of 50 micro-holes. 相似文献
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Renjie JiAuthor VitaeYonghong LiuAuthor Vitae Yanzhen ZhangAuthor VitaeFei WangAuthor Vitae 《International Journal of Refractory Metals and Hard Materials》2011,29(1):117-122
A new process of machining silicon carbide (SiC) ceramic using end electrical discharge milling is proposed in this paper. The process is able to effectively machine a large surface area on SiC ceramic with good surface quality and low cost. The effects of machining conditions on the material removal rate, electrode wear ratio, and surface roughness have been investigated. The surface microstructures machined by the new process are examined with a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and an X-ray diffraction (XRD). The results show that the SiC ceramic is removed by melting, evaporation and thermal spalling, the material from the tool electrode can transfer to the workpiece, and a combination reaction takes place during end electric discharge milling of the SiC ceramic. 相似文献
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This study proposes a novel combined process that integrates electrical discharge machining (EDM) and ultrasonic machining (USM) to investigate the machining performance and surface modification on Al–Zn–Mg alloy. In the experiment, TiC particles were added into the dielectric to explore the influence of the combined process on the material removal rate (MRR), the relative electrode wear ratio (REWR), the surface roughness and the expansion of the machined hole. The elemental distributions of titanium and carbon on the cross-section were quantitatively determined using an electron probe micro-analyzer (EPMA). Microhardness and wear resistance tests were conducted to evaluate the modifications on the machined surface caused by the combined process. The experimental results show that the combined process was associated with improved machining performance. The combination of EDM with USM yielded an alloyed layer that improved the hardness and wear resistance of the machined surface. 相似文献
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Surface integrity and material removal mechanisms associated with the EDM of Al2O3 ceramic composite
K.M. Patel Pulak M. Pandey P. Venkateswara Rao 《International Journal of Refractory Metals and Hard Materials》2009,27(5):892-899
Electric discharge machining (EDM) has been proven as an alternate process for machining complex and intricate shapes from the conductive ceramic composites. The performance and reliability of electrical discharge machined ceramic composite components are influenced by strength degradation due to EDM-induced damage. The success of electric discharge machined components in real applications relies on the understanding of material removal mechanisms and the relationship between the EDM parameters and formation of surface and subsurface damages. This paper presents a detailed investigation of machining characteristics, surface integrity and material removal mechanisms of advanced ceramic composite Al2O3–SiCw–TiC with EDM. The surface and subsurface damages have also been assessed and characterized using scanning electron microscopy (SEM). The results provide valuable insight into the dependence of damage and the mechanisms of material removal on EDM conditions. 相似文献
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Z. J. Pei P. M. Ferreira S. G. Kapoor M. Haselkorn 《International Journal of Machine Tools and Manufacture》1995,35(7)
Among the various material removal processes applicable to ceramic materials, rotary ultrasonic machining has the potential for high material removal rate while maintaining low machining pressure and resulting in less surface damage. The limitation of rotary ultrasonic machining is that only circular holes or cavities can be machined due to the rotary motion of the tool. Attempts have been made by other researchers to extend rotary ultrasonic machining process to machining flat surfaces or milling slots. However, these extensions either changed the material removal mechanisms or had some severe drawbacks. One of the reasons for this might be an insufficient understanding of the material removal mechanisms involved. In this paper, a new approach to extend rotary ultrasonic machining to face milling of ceramics is proposed, which keeps all the material removal mechanisms of rotary ultrasonic machining. The development of the experimental apparatus and the design of the cutting tool are described. Preliminary experimental results are presented and discussed. 相似文献
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This paper describes improvement of the machining characteristics of dry electrical discharge machining (dry EDM) by controlling the discharge gap distance using a piezoelectric actuator. Dry EDM is a new process characterized by small tool electrode wear, negligible damage generated on the machined surface, and significantly high material removal rate especially when oxygen gas is used. However, the narrow discharge gap length compared with conventional EDM using oil as the dielectric working fluid results in frequent occurrence of short circuiting which lowers material removal rate. A piezoelectric actuator with high frequency response was thus introduced to help control gap length of the EDM machine. To elucidate the effects of the piezoelectric actuator, an EDM performance simulator was newly developed to evaluate the machining stability and material removal rate of dry EDM. 相似文献
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Material Removal Rate,Kerf, and Surface Roughness of Tungsten Carbide Machined with Wire Electrical Discharge Machining 总被引:3,自引:0,他引:3
Aqueel Shah Nadeem A. Mufti Dinesh Rakwal Eberhard Bamberg 《Journal of Materials Engineering and Performance》2011,20(1):71-76
In this article, the effects of varying seven different machining parameters in addition to varying the material thickness
on the machining responses such as material removal rate, kerf, and surface roughness of tungsten carbide samples machined
by wire electrical discharge machining (WEDM) were investigated. The design of experiments was based on a Taguchi orthogonal
design with 8 control factors with three levels each, requiring a set of 27 experiments that were repeated three times. ANOVA
was carried out after obtaining the responses to determine the significant factors. The work piece thickness was expected
to have a major effect on the material removal rate but showed to be significant in the case of surface roughness only. Finally,
optimization of the machining responses was carried out and models for the material removal rate, kerf, and surface roughness
were created. The models were validated through confirmation experiments that showed significant improvements in machining
performance for all investigated machining outcomes. 相似文献
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This paper describes an investigation on factors determining the limits of the minimum machinable diameter of micro rods obtained by micro EDM. Possible factors which influence the limits are discharge crater size, depth of heat affected zone, residual stress, and material micro-structure. In this paper, the influences of residual stress and material micro-structure were especially examined. For the negative effects of residual stress, both residual stress already present prior to machining and residual stress generated by machining itself were investigated using tungsten and cemented tungsten carbide as micro-rod workpiece materials. To determine the effects of material micro-structure, the influence of tungsten carbide grain size on the limits of minimum machinable diameter of cemented tungsten carbide rods was investigated. Comparing the limits between poly-crystal tungsten and mono-crystal tungsten, it was found that micro-machining characteristics were affected significantly by the anisotropy of the mono-crystal tungsten. 相似文献
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G. K. Dosbaeva S. C. Veldhuis A. Elfizy G. Fox-Rabinovich T. Wagg 《Journal of Materials Engineering and Performance》2010,19(8):1193-1198
Surface quality of advanced superalloys after machining is one of the major issues in the aerospace industry because it directly
affects service characteristics of the machined part. Tool life of cemented carbide inserts with the TiAlN coating during
machining of direct aged DA 718 alloys under roughing and finishing conditions has been under study. The defect origin on
the surface of the machined part was investigated. Metallographic observations of the DA 718 were made using optical metallography
and SEM/EDS. To find out the origins of surface defect formation, the morphology of machined parts and cross sections of the
machined surfaces have been investigated. Two major categories of defects were detected on the surface of the machined part:
cracks and tears. The origin of the cracks on the machined surface is related to shearing of the primary complex TiC/NbC carbide
revealed in a structure of DA 718 alloy. At the same time, Nb-rich regions of the primary complex carbide interact with the
environment (oxygen from air) during machining with further formation of low strength oxide layer on the surface, forming
tears. 相似文献
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Ultrasonic and electric discharge machining to deep and small hole on titanium alloy 总被引:2,自引:0,他引:2
Zhao Wansheng Wang Zhenlong Di Shichun Chi Guanxin Wei Hongyu 《Journal of Materials Processing Technology》2002,120(1-3)
Being a difficult-to-cut material, titanium alloy suffers poor machinability for most cutting process, let alone the drilling of small and deep holes using traditional machining methods. Although electric discharge machining (EDM) is suitable to handle titanium alloys, it is not ideal for small and deep holes due to titanium alloys’ low heating conductivity and high tenacity. This paper introduces ultrasonic vibration into micro-EDM and analyzes the effect of ultrasonic vibration on the EDM process. A four-axis EDM machine tool which combines ultrasonic and micro-EDM has been developed. A wire electric discharge grinding (WEDG) unit which can fabricate a micro-electrode on-line, as well as a measuring unit, is set up on this equipment. With a cylindrical tool electrode, made of hard carbide, which has high stiffness, a single-side notch was made along the electrode. Ultrasonic vibration is then introduced into the micro-EDM. Experiments have been carried out and results have shown that holes with a diameter of less than Ø0.2 mm and a depth/diameter ratio of more than 15 can be drilled steadily using this equipment and technology. 相似文献