• Journal of Welding and Joining
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• v.16 no.4
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• pp.63-72
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• 1998

In this study, the effects of the current pulsing conditions, on the spatter generation rate during the $CO_2$ gas metal arc welding (GMAW) were investigated. Normally using the inverter type power supply, of which the welding current waveform was regulated to reduce the spatter generation rate, but in this study pulsing was imposed on the welding current. Observation of the metal transfer phenomena during the pulsed current GMAS indicated that the droplet transfer from the electrode via the short circuit transfer and the repelling transfer mode could be minimized by selecting optimum combinations of pulsing parameters, which include base and peak current, base and pak duration. It was also demonstrated in this study that proper combinations of the pulsing parameters led to reduce generation of spatters during GMAW shielded by $CO_2$ gas.

• Journal of Welding and Joining
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• v.10 no.4
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• pp.222-229
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• 1992

A prediction of penetration and heat affected zone by using Finite Element Method in CO$_{2}$ Arc Welding has been discussed this paper. The temperature distribution of a base metal produced by the CO$_{2}$ arc welding processing is analyzed by using a three dimensional finite element model. The common finite element program ANSYS 4.4A was employed to obtain the numerical results. Temperature dependent material properties, effect of latent heat, and the convective boundary conditions are included in the model. Numerically predicted sizes of the penetration and the heat affected zone are compared with the experimentally observed values. As a result, there was a slight difference between numerical analysis values and experimentally observed values. For in the case of heat affected zone, it was not considered a precise forced convective coefficient value, and in the case of penetration, it was not, considered a arc force.

• Journal of the KSME
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• v.22 no.1
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• pp.24-33
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• 1982

지계차는 1930 년대에 미국에서 개발되어 세계대전을 통하여 미군의 군수물자 운반에 크게 기 여하므로써 널리 알려진 물자취급(material handling)의 현대적 장비로 팰릿(pallet).컨테이너와 함께 일관수송에 있어서의 커다란 역할을 담당하고 있는 산업용 차량이다. 지계차는 크게 샤 시부분과 작업기 부분으로 구성되는데, 마스트레일은 주로 소형차에서는 생산량이 많기 때문에 압출의 제조공정으로 만들어지고 있으나 대형차는 수량이 적기 때문에 용접구조로 설계되고 있다. 마스트렝리의 중요한 특징을 말하면 (1) 폭에 비하여 길이가 긴 형강구조 (2) 레일 내폭의 공차가 비교적 엄격하다. (3) 용착량이 많아 변형되기 쉽고 일단 변형되면 교정이 어렵다. (4) 원가와 제조공정을 단축시키기 위하여 기계가공 공정을 뒤에 두지 않고 있다. 이상과 같은 특징을 가진 용접구조형 레일을 제작하는데 있어서 실제 적용된 CO2 용접 및 이의 간단한 부 착(attach)에 의한 저투자성 용접자동화 실현과정상의 제문제등을 중심으로 고찰해 보기로 한다.

• Journal of Welding and Joining
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• v.17 no.1
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• pp.116-123
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• 1999

The $CO_2$ welding with 100% $CO_2$ shielding gas is commonly used because of its cost and efficiency. Arc phenomena of the $CO_2$ welding is influenced by various factors such as chemical compositions of welding wire, shielding gas, welding condition and welding power source etc. In this study, arc phenomena is investigated by using two type of FCW(titania type, semi-metal type). Then, the welding quality and optimum welding condition can be selected. From this study, the following results were obtained; 1) In low current range(140A), FCW up to welding voltage(22V) resulted in a typical short circuit transfer. 2) In high current range(320A), the arc stability in titania FCW of a typical globular transfer is better than that of semi-metal FCW.

• Proceedings of the KWS Conference
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• 1997.10a
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• pp.229-233
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• 1997

The demand to increase productivity and quality, the shortage of skilled labour and the strict health and safety requirements have led to the development of the automated welding process to deal with many of the present problems of welded fabrication. To make effective use of the automated arc welding process, it is imperative that a mathematical model, which can be programmed easily and fed to the robot, should be developed. The objectives of the paper are to develop the mathematical equations (linear and curvilinear) for study of the relationship between process variables and bead geometry by employing a standard statistical package program, SAS and to choose the best model for automation of the $CO_2$ gas arc welding process. Mathematical models developed from experimental results can be employed to control the process variables in order to achieve the desired bead geometry based on weld quality criteria. Also these equations may prove useful and applicable for automatic control system and expert systems.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.379-381
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• 2011

본 논문에서는 피복아크용접(SMAW)을 자동용접으로(GMAW) 전환시키기 위한 기초 연구로서 GMA용접가스가 기공율에 미치는 영향을 보고자 한다. 기공율 평가를 위해 반자동 소방용 분기배관실험장치를 제작하였다. 분기배관의 기공율을 평가하기 위해 보호가스 3종(Ar, $CO_2$, 8:2 혼합가스), 전압을 변수로 설정하여 GMA용접을 실시하였다. 용접을 실시한 시편을 용접방향으로 절단하여 기공율 평가를 실시하였다.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.85-92
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• 1999

In GMAW, the spatter is generated because of the variation of the arc state. If the arc state is quantitatively assessed, the control method to make the spatter be reduced is able to develop. This study was attempted to develop the optimal model that could estimate the arc state quantitatively. To do this, the generated spatters was captured under the limited welding conditions, and the waveforms of the arc voltage and of the welding current were collected. From the collected waveforms, the waveform factors and their standard deviations were produced, and the linear and non-linear regression models constituted using the factors and their standard deviations are proposed to estimate the arc state. the performance test to the proposed models was practiced. Obtained results are as follow. From the results of correlation analysis between the factors and the amount of the generated spatters, the standard deviations of the waveform factors have more the multiple regression coefficients than the waveform factors. Because the correlation coefficient between T and {TEX}$T_{a}${/TEX}, and s[T] and s[{TEX}$T_{a}${/TEX}] was nearly one, it was found that these factors have the same effect to the spatter generation. In the regression models to estimate the arc state, it was fond that the linear and the non linear models were also consisted of similar factors. In addition, the linear regression model was assessed the optimal model for estimating the arc state because the variance of data was narrow and multiple regression coefficient was highest among the models. But in the welding conditions which the amount of the generated spatters were small, it was found that the non linear regression model had better the estimation performance for the spatter generation than the linear.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.143-153
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• 1997

In this study, bending test was performed on the real-scale, built-up beam test model fabricated by the $CO_2$ arc spot welding to evaluate the applicability of the welding method to the production of the stiffened plate in car-carrying ship. The built-up beam models which were fixed at both ends in longitudinal direction or simply supported to the rigid foundation, depending on the restraint condition of the corresponding car decks considered, were subjected to simulated design vehicle loads or concentrated point loads. During the test, the central deflection and the longitudinal bending stresses were measured from several points on the longitudinal flange face to predict the section properties of the built-up beams. The longitudinal bending stress on each spot weld were also measured to calculate the average horizontal shear force subjected to spot welds. Test results revealed that the shear strength of spot welds with their current weld nugget size and welding pitch was adequate enough to withstand the horizontal shear forces under the design vehicle loads. Although the built-up beam fabricated by the arc spot welding was a discontinuous beam, its mechanical behavior was well explained by the continuous beam theory using the effective breadth of plate. Based on test results, the criterion for the size of spot weld of which the average shear stress might meet the allowable stress requirement of AWS Code could be established.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.149-153
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• 1998

In this paper A switched mode AC/DC three phase boost converter with high power factor and sinusoidal input current waveform is analyzed and simulated. The proposed converter retain high power factor and sinusoidal input current waveform even under electric arc welder load. It is shown that experimental result and simulation waveform yield a sinusoidal input current waveform at high power factor.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.93-99
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• 1998

The effects of welding conditions of gas metal arc welding on the elements loss of solid wire, oxygen content and impact toughness of weld metals were studied. Deoxidizing elements loss was increased with increase of arc voltage in both short-circuit transfer mode and globular transfer mode. It is believed that increase of arc voltage results in increase of reaction time between elements in the droplet and surrounding gas at the end of wire and in the arc column. Based on the thermodynamic equilibrium model, the oxygen content of weld metal can be predicted with the content of silicon and manganese as following : [%O] = $K([%Si][%Mn])^{-0.25}$, K = -15518/T+6.01. The equilibrium temperature was dependent on shielding gas, and it was 187$0^{\circ}C$ for $CO_2$ gas and 180$0^{\circ}C$ for 20%$CO_2$-80%Ar gas. The oxygen content of weld metal which shows maximum impact toughness was varied with deoxidizing alloy system of wires, 0.041 wt% for Si-Mn type wire and 0.026 wt% for Si-Mn-Ti type wire.