共查询到20条相似文献,搜索用时 732 毫秒
1.
This paper describes the development of parallel spark EDM method. In the discharge circuit, the electrode is divided into multiple electrodes, each of which is electrically insulated and connected to the pulse generator through a diode. A capacitor is inserted parallel to each discharge gap between each electrode and workpiece (here workpiece is common for each electrode). Compared with conventional EDM in which only a singular discharge can be generated for each pulse, multiple discharges can dispersively be generated for each pulse in parallel spark EDM. Results of experiments on parallel spark EDM and conventional EDM show that not only is the machining process more stable, but the machining speed and surface roughness can also be improved with parallel spark EDM. 相似文献
2.
Marin Gostimirovic Pavel Kovac Milenko Sekulic Branko Skoric 《Journal of Mechanical Science and Technology》2012,26(1):173-179
The machining characteristics of electrical discharge machining (EDM) directly depend on the discharge energy which is transformed
into thermal energy in the discharge zone. The generated heat leads to high temperature, resulting in local melting and evaporation
of workpiece material. However, the high temperature also impacts various physical and chemical properties of the tool and
workpiece. This is why extensive knowledge of development and transformation of electrical energy into heat is of key importance
in EDM. Based on the previous investigations, analytical dependence was established between the discharge energy parameters
and the heat source characteristics in this paper. In addition, the thermal properties of the discharged energy were experimentally
investigated and their influence on material removal rate, gap distance, surface roughness and recast layer was established.
The experiments were conducted using copper electrode while varying discharge current and pulse duration. Analysis and experimental
research conducted in this paper allow efficient selection of relevant parameters of discharge energy for the selection of
most favorable EDM machining conditions. 相似文献
3.
Byung Han Yoo Byung-Kwon Min Sang Jo Lee 《International Journal of Precision Engineering and Manufacturing》2010,11(4):629-632
Electrical discharge machining (EDM) is a process that can be used effectively to machine conductive metals regardless of
their hardness. In the EDM process, material removal occurs because of the thermal energy of the plasma channel between the
electrode and the workpiece. During EDM, the electrode as well as the workpiece is abraded by the thermal energy. Tool wear
adversely affects the machining accuracy and increases tooling costs. Many previous studies have focused on mitigating the
problems of tool wear by investigating various EDM parameters. In this study, the tool wear problem was investigated on the
basis of the mobilities of electrons and ions in the plasma channel. The material removal volumes of both the electrode and
the workpiece were compared as functions of the gap voltage. The material removal difference according to the capacitance
was also investigated. The tool wear ratio was calculated under different EDM condition and an EDM conditions for reducing
the tool wear ratio was suggested. 相似文献
4.
Yusuf Keskin H. Selçuk Halkacı Mevlüt Kizil 《The International Journal of Advanced Manufacturing Technology》2006,28(11-12):1118-1121
Electrical discharge machining (EDM) is a non-traditional production method that has been widely used in the production of dies throughout the world in recent years. The most important performance measure in EDM is the surface roughness; among other measures material removal and tool wear rates could be listed. In this study, experiments were performed to determine parameters effecting surface roughness. The data obtained for performance measures have been analyzed using the design of experiments methods. A considerably profound equation is obtained for the surface roughness using power, pulse time, and spark time parameters. The results are discussed. 相似文献
5.
气体放电加工基础工艺试验研究 总被引:1,自引:2,他引:1
采用单因素法进行了基本的工艺参数(电参数、伺服参考电压等)对气体介质放电加工性能影响的试验研究。试验结果表明:气体介质的放电加工适于采用正极性加工。在试验加工的范围内,工件的蚀除速度和表面粗糙度值随脉冲宽度和峰值电流的增加而增加,随脉冲间隔的增加而减小。极间并联合适的电容能够使加工速度和加工表面粗糙度有所改善,并对此现象进行了分析。对于某一确定的加工参数,存在一个较佳的伺服参考电压值,使加工性能较为稳定。工具电极具有较高的旋转速度能够使气体放电加工性能得到提高。使用氧气介质能够实现快速电火花加工,并根据不同气体的物理性能对不同气体介质的加工性能进行了分析。工件表面显微硬度测试结果表明:空气中放电加工的工件的表面硬度比基体硬度高,比煤油中加工的工件表面硬度低。 相似文献
6.
7.
This article describes the experimental investigation related to creation of holes in aerospace titanium alloy workpiece using static electrode machining and electrical discharge drilling (EDD) process. Special attachment for holding and rotating the tool electrode was developed and installed on electrical discharge machining (EDM) machine by replacing the original conventional tool holder provided on die sinking EDM. The effect of input parameters such as gap current, pulse on-time, duty factor and RPM of tool electrode on output parameters for average hole circularity (Ca) and average surface roughness (Ra) have been studied. It is observed that the effect of rotating electrode machining has considerable influence on the output parameters over stationary electrode machining. The micro-graphs and photographs of few selected samples were taken by SEM and metallurgical microscope, which also commensurate with the findings of the study. 相似文献
8.
Dr H. S. Liu Y. S. Tarng 《The International Journal of Advanced Manufacturing Technology》1997,13(4):264-270
The paper describes the use of abductive networks to monitor the electrical discharge machining (EDM) process. The voltage and current across the gap between the tool and workpiece are fed into the developed networks for the recognition of various pulse types in EDM in a winner-take-all fashion. Experimental results have shown that EDM pulses can be clearly classified even with different machining conditions. Hence, a reliable technique has been developed to monitor the EDM process. 相似文献
9.
Investigation of emulsion for die sinking EDM 总被引:2,自引:2,他引:0
Yonghong Liu Renjie Ji Yanzhen Zhang Haifeng Zhang 《The International Journal of Advanced Manufacturing Technology》2010,47(1-4):403-409
Machining fluid is a primary factor that affects the material removal rate, surface quality, and electrode wear of electrical discharge machining (EDM). Kerosene is the most commonly used working fluid in die sinking EDM, but it shows low ignition temperature and high volatility; if the improper operations are undertaken, it can cause conflagration. Using distilled water or pure water as the machining fluid in EDM, no fire hazard occurs, and the working environment is well; however, using distilled water or pure water as the machining fluid in EDM, the material removal rate of machining large surface is low, and the machine tool is easily eroded. Emulsion-1 and emulsion-2 used as working fluid in die sinking EDM are developed. The compositions of emulsion-1 and emulsion-2 are introduced. In comparison with kerosene, emulsion-1 and emulsion-2 used in EDM show high material removal rate, low surface roughness, high discharge gap, and good working environment. The electrode wear ratio in emulsion-1 is lower than that in kerosene. The electrode wear ratio in emulsion-2 is higher than that in kerosene. The effects of composition and concentration of emulsifier on the emulsion property and EDM performance have been investigated. The comparative tests of EDM performance with kerosene, emulsion-1, and emulsion-2 have been done. 相似文献
10.
Orhan Gülcan İbrahim Uslan Yusuf Usta Can Çoğun 《Machining Science and Technology》2016,20(4):523-546
The main objective of this study is to investigate the effect of Cu–Cr and Cu–Mo powder metal (PM) tool electrodes on electrical discharge machining (EDM) performance outputs. The EDM performance measures used in the study are material removal rate (MRR), tool electrode wear rate (EWR), average workpiece surface roughness (Ra), machined workpiece surface hardness, abrasive wear resistance, corrosion resistance, and workpiece alloyed layer depth and composition. The EDM performance of Cu–Cr and Cu–Mo PM electrodes produced at three different mixing ratios (15, 25, and 35 wt% Cr or Mo), compacting pressures (Pc = 600, 700, and 800 MPa), and sintering temperatures (Ts = 800, 850, and 900 °C) are compared with those machined with electrolytic Cu and Cu PM electrodes when machining SAE 1040 steel workpiece. Analyses revealed that tool materials were deposited as a layer over the work surface yielding high surface hardness, strong abrasion, and corrosion resistance. Moreover, the mixing ratio, Pc, and Ts affect the MRR, EWR, and Ra values. 相似文献
11.
Yi Jiang Wansheng Zhao Xuecheng Xi Lin Gu Xiaoming Kang 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):171-183
Discharge waveforms contain information representing the gap discharge status of an EDM process. The gap discharge status has a great influence on the machining performance including the machining efficiency, workpiece surface integrity, and tool wear rate in EDM processes. In order to identify the gap discharge status effectively, wavelet transform is used to analyze the discharge waveforms. A data acquisition and processing system based on DSP is developed for high-speed wavelet transforms and related calculations. The wavelet transform result shows that each EDM pulse can be classified by judging the approximation coefficients of the wavelet transform result. Experimental results demonstrate that the wavelet transform detection is capable of capturing the primary features of each single discharge pulse, which are usually unable to be discovered by conventional discharge detection methods such as the average gap voltage detection. By analyzing the local extreme values of approximation coefficients, the numbers of different pulses within a detection time period can be identified. The gap discharge status coefficient, which is a function of the numbers of different pulses, is then calculated and used as a feedback signal to an adaptive EDM process controller. A small-hole machining test demonstrates that, with the online adaptive controller based on the wavelet transform method, the machining efficiency and stability are improved significantly. 相似文献
12.
Gyanendra Kumar Singh Vinod Yadava Raghuvir Kumar 《International Journal of Precision Engineering and Manufacturing》2010,11(4):509-518
Electro-discharge machining (EDM) characteristics of tungsten carbide-cobalt composite are accompanied by a number of problems
such as the presence of resolidified layer, large tool wear rate and thermal cracks. Use of combination of conventional grinding
and EDM (a new hybrid feature) has potential to overcome these problems. This article presents the face grinding of tungsten
carbide-cobalt composite (WC-Co) with electrical spark discharge incorporated within face of wheel and flat surface of cylindrical
workpiece. A face grinding setup for electro- discharge diamond grinding (EDDG) process is developed. The effect of input
parameters such as wheel speed, current, pulse on-time and duty factor on output parameters such as material removal rate
(MRR), wheel wear rate (WWR) and average surface roughness (ASR), are investigated. The present study shows that MRR increases
with increase in current and wheel speed while it decreases with increase in pulse on-time for higher pulse on-time (above
100 μs). The most significant factor has been found as wheel speed affecting the robustness of electro- discharge diamond
face grinding (EDDFG) process. 相似文献
13.
MICRO ELECTRICAL DISCHARGE MACHINING DEPOSITION IN AIR 总被引:1,自引:0,他引:1
JIN Baidong ZHAO Wansheng WANG Zhenlong CAO Guohui School of Mechanical Engineering Harbin Institute of Technology Harbin China 《机械工程学报(英文版)》2006,19(4):622-625
A new deposition method is described using micro electrical discharge machining (EDM) to deposit tool electrode material on workpiece in air. The basic principles of micro electrical discharge deposition (EDD) are analyzed and the realized conditions are predicted. With an ordinary EDM shaping machine, brass as the electrode, high-speed steel as the workpiece, a lot of experiments are carried out on micro EDD systematically and thoroughly. The effects of major processing parameters, such as the discharge current, discharge duration, pulse interval and working medium, are obtained. As a result, a micro cylinder with 0.19 mm in diameter and 7.35 mm in height is deposited. By exchanging the polarities of the electrode and workpiece the micro cylinder can be removed selectively. So the reversible machining of deposition and removal is achieved, which breaks through the constraint of traditional EDM. Measurements show that the deposited material is compact and close to workpiece base, whose components depend on the tool electrode material. 相似文献
14.
15.
Thermal modeling of the material removal rate and surface roughness for die-sinking EDM 总被引:3,自引:2,他引:1
K. Salonitis A. Stournaras P. Stavropoulos G. Chryssolouris 《The International Journal of Advanced Manufacturing Technology》2009,40(3-4):316-323
The die-sinking electrical discharge machining (EDM) process is characterized by slow processing speeds. Research effort has been focused on optimizing the process parameters so as for the productivity of the process to be increased. In this paper a simple, thermal based model has been developed for the determination of the material removal rate and the average surface roughness achieved as a function of the process parameters. The model predicts that the increase of the discharge current, the arc voltage or the spark duration results in higher material removal rates and coarser workpiece surfaces. On the other hand the decrease of the idling time increases the material removal rate with the additional advantage of achieving slightly better surface roughness values. The model’s predictions are compared with experimental results for verifying the approach and present good agreement with them. 相似文献
16.
针对数控电火花成型机中电火花加工间隙放电过程难以控制的问题,提出基于电火花加工间隙状态的识别和合理的伺服进给系统的电火花自适应控制技术。通过正确的间隙检测方法,配以专家系统和决策控制软件,保证数控电火花成型机的工作可靠和安全,并使长期无人控制操作成为可能,从而为数控电火花成型机的自适应控制技术研究提供了理论依据。 相似文献
17.
José Carvalho Ferreira 《The International Journal of Advanced Manufacturing Technology》2007,34(11-12):1120-1132
An experimental research study intended for the application of a planetary electrical discharge machining (EDM) process with copper-tungsten (Cu-W) electrodes in the surface micro-finishing of die helical thread cavities made with AISI H13 tool steel full-hardened at 53 HRC is presented. To establish the EDM parameters’ effect on various surface finishing aspects and metallurgical transformations, three tool electrode Cu-W compositions are selected, and operating parameters such as the open-circuit voltage (U 0), the discharge voltage (u e), the peak discharge current (î e), the pulse-on duration (t i), the duty factor (τ) and the dielectric flushing pressure (p in), are correlated. The researched machining characteristics are the material removal rate (MRR—V w), the relative tool wear ratio (TWR—?), the workpiece surface roughness (SR—Ra), the average white layer thickness (WLT—e wl) and the heat-affected zone (HAZ—Z ha). An empirical relation between the surface roughness (SR—Ra) and the energy per discharge (W e) has been determined. It is analysed that copper-tungsten electrodes with negative polarity are appropriate for planetary EDM die steel surface micro-finishing, allowing the attaining of good geometry accuracy and sharp details. For die steel precision EDM, the relative wear ratio optimum condition and minor surface roughness takes place at a gap voltage of 280 V, discharge current of 0.5–1.0 A, pulse-on duration of 0.8 μs, duty factor of 50%, dielectric flushing pressure of 40 kPa and copper tungsten (Cu20W80) as the tool electrode material with negative polarity. The copper-tungsten electrode’s low material removal rate and low tool-wear ratio allows the machining of EDM cavity surfaces with an accurate geometry and a “mirror-like” surface micro-finishing. A planetary EDM application to manufacture helical thread cavities in steel dies for polymer injection is presented. Conclusions are appointed for the planetary EDM of helical thread cavities with Cu-W electrodes validating the accomplishment as a novel technique for manufacturing processes. 相似文献
18.
19.
A. B. Pandey P. K. Brahmankar 《The International Journal of Advanced Manufacturing Technology》2016,86(9-12):2837-2849
Electrical Discharge Machining (EDM) is very popular for machining conductive metal matrix composites (MMCs) because the hardness rendered by the ceramic reinforcements to these composites causes very high tool wear and cutting forces in conventional machining processes. EDM requires selection of a number of parameters for desirable results. Inappropriate parameter selection can lead to high overcuts, tool wear, excessive roughness, and arcing during machining and adversely affect machining quality. Arcing leads to short circuit gap conditions resulting in large energy discharges and uncontrolled machining. Arcing is a detrimental phenomenon in EDM which causes spoiling of workpiece and tool electrode and tends to damage the power supply of EDM machine. Parameter combinations that lead to arcing during machining have to be identified and avoided for every tool, work material, and dielectric combination. Proper selection of parameter combinations to avoid arcing is essential in EDM. In the work, experiments were conducted using L27 design of experiment to determine the parameter settings which cause arcing in EDM machining of TiB2p reinforced ferrous matrix composite. Important EDM process parameters were selected in roughing, intermediate, and finishing range so as to study the occurrence of arcing. Using the experimental data, an artificial neural network (ANN) model was developed as a tool to predict the possibility of arcing for selected parameter combinations. This model can help avoid the parameter combinations which can lead to arcing during actual machining using EDM. The ANN model was validated by conducting validation experiments to ensure that it can work accurately as a predicting tool to know beforehand whether the selected parameters will lead to arcing during actual machining using EDM. Validation results show that the ANN model developed can predict arcing possibility accurately when the depth of machining is included as input variable for the model. 相似文献
20.
Development of an intelligent process model for EDM 总被引:1,自引:1,他引:0
S. N. Joshi S. S. Pande 《The International Journal of Advanced Manufacturing Technology》2009,45(3-4):300-317
This paper reports the development of an intelligent model for the electric discharge machining (EDM) process using finite-element method (FEM) and artificial neural network (ANN). A two-dimensional axisymmetric thermal (FEM) model of single-spark EDM process has been developed based on more realistic assumptions such as Gaussian distribution of heat flux, time- and energy-dependent spark radius, etc. to predict the shape of crater cavity, material removal rate, and tool wear rate. The model is validated using the reported analytical and experimental results. A neural-network-based process model is proposed to establish relation between input process conditions (discharge power, spark on time, and duty factor) and the process responses (crater geometry, material removal rate, and tool wear rate) for various work—tool work materials. The ANN model was trained, tested, and tuned using the data generated from the numerical (FEM) simulations. The ANN model was found to accurately predict EDM process responses for chosen process conditions. It can be used for the selection of optimum process conditions for EDM process. 相似文献