• 제목/요약/키워드: Spark Discharge

검색결과 155건 처리시간 0.018초

건성 와이어방전가공 프로세스 특성에 관한 실험적 연구 (Experimental Study on Characteristics of Dry Wire Electrical Discharge Machining (EDM) Process)

  • 이상원;김홍석
    • 한국정밀공학회지
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    • 제27권1호
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    • pp.11-17
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    • 2010
  • This study investigates the non-traditional manufacturing process of dry wire electrical discharge machining (EDM) in which liquid dielectric is replaced by a gaseous medium. Wire EDM experiments of thin workpieces were conducted both in wet and dry EDM conditions to examine the effects of spark cycle (T), spark on-time ($T_{on}$), thickness of work pieces, and work material on machining performance. The material removal rate (MRR) in the dry wire EDM case was much lower than that in the wet wire EDM case. In addition, the thickness of workpiece and work-material were found to be critical factors influencing the MRR for dry EDM process. The relative ratios of spark, arc and short circuit were also calculated and compared to examine the effectiveness of processes of dry and wet wire EDM.

Generation of Model Diesel Particles by Spark Discharge and Hydrocarbon Condensation

  • Kim, Hak-Joon;Kim, Jin-Ho;Choi, Young-Joo;Oh, Hyen-Chul;Chu, Jung-Bum;Kim, Sang-Soo
    • Journal of Mechanical Science and Technology
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    • 제20권11호
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    • pp.1972-1979
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    • 2006
  • This study was conducted in order to generate model particles which were similar to particles in diesel emission. Spark discharge was used for carbon agglomerates and hydrocarbon condensation for particles that consist of carbon agglomerates and hydrocarbon. The size of the carbon agglomerates, whose mean size were 30 and 70 nm, ranged between 15 and 200 nm, and the total number concentration of the particles ranged from 3 to $5{\times}10^7#/cm^3$ as the controllable variables in spark discharge generator changed. The result of the hydrocarbon condensation experiment showed that the final sizes of the particles enlarged by condensation did not depend on the initial sizes, but the maximum condensational growth of carbon agglomerates by dodecane ($C_{12}H_{26}$) condensation was 112 times the initial size of 40 nm, while the size of the agglomerates by benzene ($C_6H_6$) was 3.25 times its initial size.

다회수 스파크 점화기관의 기관성능에 관한 연구 (A study on the engine performance in a multiple spark ignition engine)

  • 이성열;한병호
    • 오토저널
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    • 제10권4호
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    • pp.66-74
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    • 1988
  • The ignition quality of ignition system is influenced by spark energy, discharge pattern of spark energy and spark duration. In this paper, the characteristics of multiple spark ignition system have been investigated for various number of spark and spark interval. The results, which were compared with those obtained with a standard single spark ignition, show that engine output is increased, and lean misfire limit is extended with the multiple spark ignition system. The most effective number of spark at the most effective spark interval that are determined by engine performance test, were 6 times spark at 0.02ms spark interval. For the above condition of spark, engine torque was increased about 20% comparing with conventional ignition system and lean misfire limit was extended to air-fuel ratio 22.5:1. This study researched the rate of heat release and quantity of heat release influenced by a condition of spark on the mass burned in order to investigate the relationship between the rate of mass burned and number of spark times.

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A Pulser System with Parallel Spark Gaps at High Repetition Rate

  • Lee, Byung-Joon;Nam, Jong-Woo;Rahaman, Hasibur;Nam, Sang-Hoon;Ahn, Jae-Woon;Jo, Seung-Whan;Kwon, Hae-Ok
    • 전기전자학회논문지
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    • 제15권4호
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    • pp.305-312
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    • 2011
  • A primary interest of this work is to develop an efficient and powerful repetitive pulser system for the application of ultra wide band generation. The important component of the pulser system is a small-sized coaxial type spark gap with planar electrodes filled with SF6 gas. A repetitive switching action by the coaxial spark gap generates two consecutive pulses in less than a microsecond with rise times of a few hundred picoseconds (ps). A set of several parameters for the repetitive switching of the spark gap is required to be optimized in charging and discharging systems of the pulser. The parameters in the charging system include a circuit scheme, circuit elements, the applied voltage and current ratings from power supplies. The parameters in the discharging system include the spark gap geometry, electrode gap distance, gas type, gas pressure and the load. The characteristics of the spark gap discharge, such as breakdown voltage, output current pulse and recovery rate are too dynamic to control by switching continuously at a high pulse repetition rate (PRR). This leads to a low charging efficiency of the spark gap system. The breakthrough of the low charging efficiency is achieved by a parallel operation of two spark gaps system. The operational behavior of the two spark gaps system is presented in this paper. The work has focused on improvement of the charging efficiency by scaling the PRR of each spark gap in the two spark gaps system.

스파크 음원을 이용한 장벽의 회절음장에 관한 실험 연구 (Experimental Study on Sound Diffraction over Barrier Using a Spark Discharge Sound Source)

  • 주진수
    • 소음진동
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    • 제9권3호
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    • pp.466-471
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    • 1999
  • The prediction methods of diffraction field in barrier has beenreported much about the infinite length barrier and it is very few work that reasonable sound source was used in experiment. This study, however, has worked about the several model barrier with acoustic scale model experiment. In the case of scale model experiment, it is difficult to use the kind of source with sufficiently characteristics. A spark discharge sound source with the high repeatability, broad band spectra, small size and omnidirectivity has veen used for the prediction of diffraction field. Several model barriers with different length on the ground were considered for the experiment and compared with the the results calculated by the approximation.

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Trigged Spark Gap의 고전압 방전제어특성 연구 (Characteristics of High Voltage Discharge using Triggered Spark Gap)

  • 손윤규;김광기;박상욱;조무현
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 하계학술대회 논문집 E
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    • pp.1816-1818
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    • 1997
  • A triggered sparkp gap switch was fabricater and its high-voltage discharge characteristics were studied. The switch is composed of two main electrodes and one trigger electrode which is placed perpendicular to the main one. Spark gap distance was fixed by 25 mm. This device has been operated without self firing at the pulse repetition frequency from 1 to 20 Hz limited by the charging current, and the hold-off voltage from 10 to 30kV. An IGBT switch and igniter coil (originally used in a car) were adopted for a trigger circuit. In this article preliminary switch characteristics of the spark gap switch are reported with the emphasis on the description of the trigger circuit.

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Synthesis and Characterization of TiO2, Cu2O and Al2O3 Aerosol Nanoparticles Produced by the Multi-Spark Discharge Generator

  • Efimov, Alexey;Lizunova, Anna;Sukharev, Valentin;Ivanov, Victor
    • 한국재료학회지
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    • 제26권3호
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    • pp.123-129
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    • 2016
  • The morphology, crystal structure and size of aerosol nanoparticles generated by erosion of electrodes made of different materials (titanium, copper and aluminum) in a multi-spark discharge generator were investigated. The aerosol nanoparticle synthesis was carried out in air atmosphere at a capacitor stored energy of 6 J, a repetition rate of discharge of 0.5 Hz and a gas flow velocity of 5.4 m/s. The aerosol nanoparticles were generated in the form of oxides and had various morphologies: agglomerates of primary particles of $TiO_2$ and $Al_2O_3$ or aggregates of primary particles of $Cu_2O$. The average size of the primary nanoparticles ranged between 6.3 and 7.4 nm for the three substances studied. The average size of the agglomerates and aggregates varied in a wide interval from 24.6 nm for $Cu_2O$ to 46.1 nm for $Al_2O_3$.

Influence of Discharge Conditions on the Ignitability of Lycopodium Streams Due to a Single Capacitance Discharge Spark

  • Park, K. S.;M. Yamaguma;T. Kodama;J. H. Joung;Kim, T. Y.;M. Nifuku;M. Takeuchi
    • KIEE International Transactions on Electrophysics and Applications
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    • 제3C권3호
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    • pp.99-105
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    • 2003
  • The influence of discharge conditions, including the resistance of the sparking circuit, the shape of the electrodes and the width of the falling dust on the ignitability of lycopodium streams were investigated. Discharge characteristics and the ignition phenomena were also explored. When a 100 ㏀ resistor was connected in series with the sparking circuit, the lowest level of minimum ignition energy (MIE) was attained for lycopodium streams. Simultaneously, the area where flammable gas generated increased and the duration of flammable gas generation decreased. That is, the ignita-bility of lycopodium streams depended strongly on the discharge power and discharge duration. Electrodes with sharp tips gave smaller MIEs than those with round tips in a capacitive-inductive sparking circuit, while shape made no difference in a capacitive-resistive circuit. Streams that were too narrow required a considerable amount of energy for ignition.

저항회로의 개폐불꽃에 의한 폭발성 가스의 점화한계에 관한 연구 (A Study on The Ignition Limit of Flammable Gases by Discharge Spark of Resistive Circuit)

  • 이춘하
    • 한국가스학회지
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    • 제1권1호
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    • pp.106-112
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    • 1997
  • 본 연구는 직류 저항회로의 개폐불꽃에 의한 폭발성 가스의 점화한계를 실험적으로 고찰하였다. 실험은 IEC형 불꽃점화 시험장치의 폭발용기에 폭발성 가스(메탄-공기 프로판-공기, 에틸렌-공기, 수소-공기)를 각각 넣고 텅스텐 전극과 카드뮴 전극사이에서 발생하는 3,200회의 개폐불꽃에 의한 점화유무를 확인하므로서 점화한계를 구하였다. 또한 실험장치의 점화감도교정을 실험한 후에 실시하므로서 실험의 정확성을 기하였다. 실험결과 최소 점화 전류값을 갖는 최소점화한계농도는 메탄-공기 8.3 [$Vol\%$], 프로판-공기 5.25[$Vol\%$], 에틸렌-공기 7.8[$Vol\%$], 수소-공기 21[$Vol\%$]로서 기존의 실험결과와 유사한 결과를 나타내었다. 또한 최소점화한계농도에서 전압과 최소점화잔류와의 관계를 구한 결과 최소점화한계는 메탄, 프로판, 에틸렌, 수소가스의 순서로 낮아졌고 점화전류의 크기는 전원전압의 크기와 반비례하고, 전극의 과열현상으로 인하여 전압 약 20(V)이하에서는 최소점화전류가 2(A)를 넘으면서 심화한계곡선이 급격히 상승한다는 것 등을 알 수 있었다.

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a-C:H Films Deposited in the Plasma of Surface Spark Discharge at Atmospheric Pressure. Part I: Experimental Investigation

  • Chun, Hui-Gon;K.V. Oskomov;N.S. Sochungov;Lee, Jing-Hyuk;You, Yong-Zoo
    • 한국표면공학회지
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    • 제36권5호
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    • pp.357-363
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    • 2003
  • The aim of this work is the synthesis of a-C:H films from methane gas using surface spark discharge at the atmospheric pressure. Properties of these films have been investigated as functions of energy W delivered per a methane molecule in the discharge. The method enables the coatings to be deposited with high growth rates (up to $100 \mu\textrm{m}$/hour) onto large-area substrates. It is shown that the films consist of spherical granules with diameter of 20∼50 nm formed in the spark channel and then deposited onto the substrate. The best film characteristics such as minimum hydrogen-to-carbon atoms ratio H/C=0.69, maximum hardness $H_{v}$ =3 ㎬, the most dense packing of the granules and highest scratch resistance has been obtained under the condition of highest energy W of 40 eV. The deposited a-C:H coatings were found to be more soft and hydrogenated compared to the diamond-like hydrogenated (a-C:H) films which obtained by traditional plasmaenhanced chemical vapor deposition methods at low pressure (<10 Torr). Nevertheless, these coatings can be potentially used for scratch protection of soft plastic materials since they are of an order harder than plastics but still transparent (the absorption coefficient is about $10^4$$10^{5}$ $m^{-1}$ At the same time the proposed method for fast deposition of a-C:H films makes this process less expensive compared to the conventional techniques. This advantage can widen the application field of. these films substantially.y.