• Journal of Welding and Joining
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• 제23권1호
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• pp.41-47
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• 2005

Arc pressure is one of important factors in understanding physical arc phenomena. Especially it affects on the penetration, size and shape of TIG welding. Some researches were reported on the effect of arc pressure in low and middle current region. But there are not any research in high current region. The purpose of this study is to investigate the arc pressure distribution with mixing ratio of shield gas such as Ar and He gases. A Cu block with water cooling was specifically designed and used as an anode electrode in order to measure the arc pressure in high current region. Then, the arc pressure distribution was measured with change in welding current and mixing ratio of shield gases. The arc force was obtained by numerically integrating the measured results. As the results, it was shown that the arc pressure was concentrated at the central part of the arc in middle and high current regions when a pure Ar gas was used. In case of Ar + He mixing gas, the arc pressure was much lower than that of pure Ar gas. In addition, it was widely distributed to radial direction.

• Journal of Welding and Joining
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• 제27권2호
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• pp.44-50
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• 2009

The characteristics of arc pressure, current density and heat flux distribution are important factors in understanding physical arc phenomena, which will have a marked effect on the penetration, size and shape of a weld in TIG welding. The purpose of this study is to find out the effect of the heat flux on the melting efficiency and penetration shape in TIG welding using the results of the previous investigators. The conclusions obtained permit to draw a proper method which derived the heat flux distributions by arc pressure distribution measurements, but previous researchers calculated heat flux and current distribution with the heat intensity measurements by the calorimetry. Heat flux of Ar gas arc was concentrated at the central part and distributed low from the arc axis to the radial direction, that of He mixing arc was lower than that of Ar gas, and it was wide distributed to radial direction. That showed a similar characteristic with the Nestor's by calorimetry calculated values. Throughout heat flux drawn in this study was discussed melting efficiency and penetration shape on Ar gas and He mixing gas arc.

• 한국정밀공학회지
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• 제25권7호
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• pp.124-130
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• 2008

The effect of nitrogen gas pressure in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. The surface roughness, micro-particle, micro-hardness, coated thickness, atomic distribution of TiN, and adhesion strength are measured fur various nitrogen gas pressures. It has been shown that the nitrogen gas pressure has a considerable effect on the surface roughness, adhesion strength, atomic distribution of TiN, and surface deposition of TiN of the high speed steels but that it has little influence on the micro-hardness and coated thickness.

• 대한전기학회논문지
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• 제45권3호
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• pp.415-425
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• 1996

This study presents an analytical method of solving the behaviors of arc plasma in a nozzle constricting transferred-type torch and purposes to obtain the basic data for the design of a plasma torch, which can be obtained from the temperature, pressure, velocities and voltage distributions. We have to solve some conservation equations simultaneously and need to know the exact thermal gas properties in order to obtain the correct behaviors of arc plasma. It is also necessary to give the relevant physical or geometric boundary conditions. For the simplicity of analysis, we assumed that (a) the plasma flow is laminar, (b)the local thermodynamic equilibrium, i.e. LTE, prevails over the entire arc column region. The electrode sheath effects were neglected and the nozzle area was excluded from the analysis by assuming that the current flow into the nozzle is zero. We solved the momentum transfer equation including the self-magnetic pinch effect, and obtained the temperature distribution from the energy conservation equation. From this temperature, we could get arc voltage distribution. (author). refs., figs., tabs.

• Journal of Welding and Joining
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• 제22권6호
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• pp.50-56
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• 2004

MlAB(magnetically impelled arc butt) welding is a sort of pressure welding method by melting two pipe sections with high speed rotating arc and upsetting two pipes in the axial direction. The electro-magnetic force, the driving force of the arc rotation, is generated by interaction of arc current and magnetic field induced from the magnetic flux generator in the welding system. In this study, an openable coil system for the generation of magnetic flux and a 3-dimensional numerical model for analyzing the electro-magnetic field were proposed. Through the fundamental numerical analyses, a magnetic concentrator was adopted for smoothing the magnetic flux density distribution in the circumferential direction. And then a series of numerical analysis were performed for investigating the effect of system parameters on the magnetic flux density distribution in the interested welding area.. Numerical quantitative analyses showed that magnetic flux density distribution generated from the proposed coil system is mainly dependent on the exciting current in the coil and the position of coil or concentrator from the pipe outer surface. And the gap between pipe ends and arc current are also considered as important factors on arc rotating behavior.

• 대한전기학회논문지
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• 제36권9호
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• pp.655-659
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• 1987

This study presents a model of the electrical characteristics of the high-pressure mercury vapour arc discharge. Energy balance equation per unit volume of the arc tube is converted into the one per unit length by assuming the parabolic radial temperature distribution and integrating over the cross-section of the tube. Using this energy balance equation, together with the circuit equation and Ohm's law, the arc voltage and current variation for 1 cycle is numerically calculated and a good result is obtained. A simple method to calculate the axis temperature of the arc tube and the radiation output is also presented.

• 전기의세계
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• 제22권5호
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• pp.19-32
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• 1973

This paper treats with some of plasma jet behaviors under magnetic field for the purpose of controlling important characteristics of plasma jet in the practices of material manufacturings. Under the existence and non-existence of magnetic field, the pressure distribution, flame length, stability and noise of plasma jet are comparatively evaluated in respect of such parameters as are current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle. The results are as follows: 1) the pressure, the length and the noise of plasma jet rise gradually with the increase of are current, and have high values under identical arc current as the diameter of nozzle increases, but reverse phenomenon tends to appear in the noise. 2) The pressure, the flame length and the noise increase with the increased quantity of argon flow, and the rising slope of noise is particularly steep. Under magnetic field, the quantity of argon flow in respect of flame length has the critical value of 80(cfh). 3) The pressure and length of flame decrease with small gradient value as the length of gap increases, but the noise tends to grow according to the increase of nozzle diameter. 4) The pressure and the length of jet flame decrease inversly with the increase of magnetic flux density, which have one critical value in the 100 amps of arc current and two values in 50 amps. The pressure of jet flame can be below atomospher pressure in strong magnetic field. 5) "The constriction length of nozzle has respectively the critical value of 6(mm) for pressure and 23(mm) for the length of flame. 6) Fluctuations in the wave form of voltage become greater with the increase of argon flow and magnetic flux density, but tends to decrease as arc current increases, having the frequency range of 3-8KHz. The wave form of noise changes almost in parallel with that of voltage and its changing value increases with argon flow, arc current and magnetic flux density, having the freuqency range of 6-8KHz. The fluctuation of jet presurre is reduced with the increase of argon flow and magnetic flux density and grows with arc current.rent.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.477-482
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• 2001

A study was performed to determine the optimum height for an arc air gouging of temporary attachments, which were attached at the pressure vessel made of low alloy steel. Frequently, the crack occurred in the base metal by the excessive heat input during an arc air gouging process to remove the temporary attachments. A numerical analysis by 2-dimensional finite element method was performed to calculate the temperature distribution in the base metal during the removal of temporary attachments. And then the mock-up test was performed to verify the numerical results. Numerical values showed good agreement with the experimental results. These results indicated that the defects due to the excessive heat input during an arc air gouging were dependent on the height of temporary attachments remained above hie main products.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.167-169
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• 1998

Recently $SF_6$ gas circuit breakers utilizing the thermal-expansion principle are increasingly used in distribution power system. Active researches and developments have been conducted to reduce the size and weight, and to improve the interrupting performance of the circuit breakers. It was first developed a programme which could show the hot gas flowing into the thermal-expansion arc chamber. This programme, using so-called FLIC method basically, adopted 'Simplified Enthalpy Arc Model' which was somewhat modified to estimate the arc quenching process. The computation by it was compared with the measured results of the pressure rise in the chamber, and both showed fairly good agreement.

• 한국진공학회지
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• 제9권3호
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• pp.207-215
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• 2000

진공증착 및 이온플레이팅 방법을 이용하여 냉간 압연된 강판상에 알루미늄피막을 형성시킨 후, 증발율 및 증기분포 변화를 측정하고 각 증착방법에서의 증발율에 따른 증기분포 변화를 비교 및 검토하였다. 본 실험에서의 이온플레이팅은 증발원 근처에 이온화 전극을 설치하는 방법으로 고전류 아크방전을 유도하여 $10^{-4}$ Torr 이하에서도 기존의 이온플레이팅에 비해 높은 이온화율을 얻을 수 있는 아크방전 유도형 이온플레이팅(Arc-induced ion Plating; AIIP) 방법을 이용하였다. 전자빔을 이용하면서 알루미나 크루시블을 사용하여 알루미늄을 증발시킬 경우 분당 2.0 $\mu\textrm{m}$이상의 높은 증발율을 얻을 수 있었으며, 이온플레이팅의 경우 이온화된 증기의 상호작용에 따른 산란 효과로 증발율이 다소 낮아짐을 알 수 있었다. $cos^{n/\phi}$로 이루어지는 증기분포의 결정인자(n)의 값이 진공증착의 경우는 1에 근접하는 것으로 나타났고 AIIP의 경우는 2 또는 그보다 더 큰 값으로 이루어지는 것을 확인하였다. 이로부터 이온플레이팅의 경우 이온화율 또는 기판 바이어스 전압의 효과가 다른 조건에 비해 증기분포에 더 크게 영향을 미치는 것을 확인할 수 있었다.