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1.
Micro electro discharge machining (micro EDM) is suitable for machining micro holes on metal alloy materials, and the micro holes can be machined even to several microns by use of wire electro discharge grinding (WEDG) of micro electrodes. However, considering practicability of micro holes <Φ100 μm in batch processing, the controllable accuracy of holes’ diameter, the consistency accuracy of repeated machining and the processing efficiency are required to be systematically improved. On the basis of conventional WEDG method, a tangential feed WEDG (TF-WEDG) method combined with on-line measurement using a charge coupled device (CCD) was proposed for improving on-line machining accuracy of micro electrodes. In TF-WEDG, removal resolution of micro-electrode diameter (the minimum thickness to be removed from micro electrode) is greatly improved by feeding the electrode along the tangential direction of wire-guide arc, and the resolution is further improved by employing negative polarity machining. Taking advantage of the high removal resolution, the precise diameter of micro-electrode can be achieved by the tangential feed of electrode to a certain position after diameter feedback of on-line measurement. Furthermore, a hybrid process was presented by combining the TF-WEDG method and a self-drilled holes method to improve the machining efficiency of micro electrodes. A cyclic alternating process of micro-electrode repeated machining and micro holes’ drilling was implemented for array micro holes with high consistency accuracy. Micro-EDM experiments were carried out for verifying the proposed methods and processes, and the experimental results show that the repeated machining accuracy of micro electrodes was less than 2 μm and the consistency accuracy of array micro holes was ±1.1 μm. 相似文献
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In recent years, the need for products containing micro-features has shown a pronounced and steady growth in several fields of application. For the development of micro-holed devices, one of the most important technologies is micro-EDM (Electro Discharge Machining). Micro-EDM can be considered as an ideal process to obtain burr-free micron-size features with high aspect ratios. In particular, micro-EDM is a non-contact material removal process in which rapid electric spark discharges remove the material composing the workpiece by means of melting and vaporizing phenomena. The present work deals with the fabrication of micro holes using micro-EDM technology. The investigation focuses on the influence of different electrodes and workpiece materials on the process performance, expressed in terms of tool wear ratio. In particular, the influence of four different workpiece materials (stainless steel, titanium, magnesium and brass), three electrode materials (copper, brass and tungsten carbide) and two different electrode shapes (cylindrical and tubular) was investigated. Moreover, an analysis of the geometrical characteristics of the micro holes in terms of conicity and diametrical overcut was carried out. An influence of electrode geometries, electrode material and workpiece material on the final output was found. 相似文献
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In servo-scanning 3D micro electro discharge machining (SS-3D MEDM), the depth errors of 3D micro cavities are accumulated layer by layer due to the contour scanning process with keeping discharge gap for compensating axial electrode wear in real time. In this research, the errors’ causes were analyzed, and then a layer depth constrained algorithm (LDCA) and an S-curve accelerating algorithm (SCAA) were proposed to reduce the depth errors. By LDCA, over-cutting errors can be avoided by controlling a tool-electrode feed maximum at every scanning spot. As a supplementary algorithm for LDCA, SCAA can compensate insufficient-machining errors at start and end of scanning paths. Implementation process and control strategy of the algorithms were also described. The purpose of this research is to efficiently machine complex 3D micro-cavities with high accuracies of shape and surface. By use of computer-aided manufacturing software of Pro/Engineer to plan complex 3D scanning paths, machining experiments were carried out to verify the proposed algorithms. The experimental results show: Typical 3D micro cavities <800 μm can be automatically machined, and the machining accuracies of micro surfaces and edges are obviously improved, and the depth errors can be controlled within 2 μm, and the material removal rate reaches 2.0 × 104 μm3/s with tool electrode of ∅80 μm and its rotational speed of 1000 r/min. In addition, the 3D micro cavities designed on unknown edge or hollow workpieces can be successfully formed. 相似文献
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In electrical discharge machining, both the gas and liquid dielectric have unique advantages and inevitable disadvantages. The mist medium with a special property between gas with liquid is expected to have a better performance in EDM. In this paper, the performance of mist deionized water jet has been studied based on the disadvantages of deionized water in deep micro hole drilling: electrolysis action, electrophoresis action and gap-contamination by debris. Based on the analyzation on the advantages of mist jet, three projects of experiments have been done to verify its performance on the suppressing of electrolysis action and improving the debris exhaust. The results show that the micro EDM drilling with high machining speed and accuracy can be realized with mist jet. This method is particularly effective in deep micro hole drilling, since deeper holes can be obtained at faster machining speed with mist jet due to its significant improvement in debris exhaust. 相似文献
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制作一种电火花小孔加工用Cu-Ni复合电极,其原理是基于电镀层和基体材料性能的差异,改变电极材料电蚀性能,保证电极端面和侧面的均匀损耗。在D703F型高速电火花小孔加工机床上,用Cu-Ni电极加工1Cr18Ni9Ti不锈钢材料,与常用的普通铜管电极对比。结果表明:在相同的加工条件下,Cu-Ni复合电极的电极损耗明显降低,同时改善了因电极损耗引起的被加工工件的尺寸精度和形状精度。 相似文献
6.
Ali Ozgedik Can Cogun 《The International Journal of Advanced Manufacturing Technology》2006,27(5-6):488-500
In this study, the variations of geometrical tool wear characteristics – namely, edge and front wear – and machining performance
outputs – namely, workpiece removal rate, tool wear rate, relative wear and workpiece surface roughness – were investigated
with varying machining parameters. Experiments were conducted using steel workpieces and round copper tools with a kerosene
dielectric under different dielectric flushing conditions (injection, suction and static), discharge currents and pulse durations.
The experiments have shown that machining parameters and dielectric flushing conditions had a large effect on geometric tool
wear characteristics and machining performance outputs. Additionally, published research on tool wear is presented in detail
in this study. 相似文献
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Hard-to-machine alloys are commonly used for industrial applications in the aeronautical, nuclear and automotive sectors, where the materials must have excellent resistance to corrosion and oxidation, high temperature resistance and high mechanical strength. In this present study the influence of different parameters of the electrical discharge machining process on surface roughness, electrode wear and material removal rate have been studied. Regression techniques are employed to model arithmetic mean deviation Ra (μm), peak count Pc (1/cm), material removal rate MRR (mm3/min) and electrode wear EW (%). All these parameters have been studied in terms of current intensity supplied by the generator of the electrical discharge machine I (A), pulse time ti (μs), duty cycle η and open-circuit voltage U (V). This modelling allows us to obtain mathematical data and models to predict that the most influential factor in MRR and Ra is the current intensity and in the case of EW and Pc is the pulse time. 相似文献
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介绍基于立体光成形(SLA)EDM电极的加工工艺。该工艺将CAD、SAL壳形铸造与真空离心铸造相结合,特别 适宜具有微形复杂形状EDM电极的单件、小批量生产,并使传统分散、多工序的EDM电极加工工艺实现了集成化和自 动化。 相似文献
10.
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
11.
F.-T. Weng M.-G. Her 《The International Journal of Advanced Manufacturing Technology》2002,19(4):266-270
The micro machining of copper plates by the electrical discharge machining (EDM) process is described. Tungsten carbide was
selected as the material for the electrode. Experiments were carried out on a conventional CNC-EDM machine to investigate
machining of micro holes, and micro slots. The results show that micro holes, and micro slots can be successfully processed
on a conventional CNC-EDM machine. To improve the productivity of micro parts using the EDM process, a batch production method
of micro EDM using multi-electrodes has been studied. A new technique for preparing multi-electrodes has been developed. Results
also show that the batch production of micro parts using EDM is feasible and that the batch production of micro parts using
EDM process with multi-electrodes is very effective. 相似文献
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微细电火花加工中电极材料的蚀除机理研究 总被引:10,自引:0,他引:10
在微细电火花加工过程中 ,由于放电时间极短 ,使得其阴阳两极的电极材料蚀除过程产生较大的差异。本文应用传热学和电场的基本理论 ,分别对微细电火花加工阴阳两极的材料蚀除机理进行了理论研究 ,得出了在窄脉宽微细电火花加工中 ,尽量缩短脉宽可提高阳极材料的去除效率 ,同时又不会明显增加阴极材料损耗的结论。为微细电火花加工脉冲电源设计及加工工艺的改进提供了理论依据 相似文献
15.
陈德忠 《世界制造技术与装备市场》2003,(1):30-34
通过IMT2002展出的低速走丝电火花线切割机床(LSWEDM),数控电火花成形机床(NCSEDM),高速小孔电火花加工机床(HSEDM)的新产品,新技术、新工艺介绍,结合我国情况对EDM市场进行了分析。 相似文献
16.
电极材料对电火花加工质量影响的分析 总被引:3,自引:0,他引:3
对电火花加工中电极材料的合理选取作了详细的分析和探讨,并用实验结果分析了电极材料性能对加工质量的影响,说明了电极材料是影响电火花加工质量的一个重要因素。 相似文献
17.
A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a wire electrode made of tungsten. The problem of the wire electrode wear was eliminated by the use of the wire electrochemical turning (WECT) method in which the tungsten wire electrode is continuously running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of wire guide; disk-shaped WC guide, laminated wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C1, and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte. 相似文献
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Micro milling is widely used to manufacture miniature parts and features at high quality with low set-up cost. To achieve a higher quality of existing micro products and improve the milling performance, a reliable analytical model of surface generation is the prerequisite as it offers the foundation for surface topography and surface roughness optimization. In the micro milling process, the stochastic tool wear is inevitable, but the deep influence of tool wear hasn't been considered in the micro milling process operation and modeling. Therefore, an improved analytical surface generation model with stochastic tool wear is presented for the micro milling process. A probabilistic approach based on the particle filter algorithm is used to predict the stochastic tool wear progression, linking online measurement data of cutting forces and tool vibrations with the state of tool wear. Meanwhile, the influence of tool run-out is also considered since the uncut chip thickness can be comparable to feed per tooth compared with that in conventional milling. Based on the process kinematics, tool run-out and stochastic tool wear, the cutting edge trajectory for micro milling can be determined by a theoretical and empirical coupled method. At last, the analytical surface generation model is employed to predict the surface topography and surface roughness, along with the concept of the minimum chip thickness and elastic recovery. The micro milling experiment results validate the effectiveness of the presented analytical surface generation model under different machining conditions. The model can be a significant supplement for predicting machined surface prior to the costly micro milling operations, and provide a basis for machining parameters optimization. 相似文献