• 동력기계공학회지
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• 제21권5호
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• pp.86-91
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• 2017

Friction Stir Welding (FSW) is useful technique to join aluminum alloy with energy efficient and environment friendly. In this paper, the design of experiment with three-way factorial design was adopted for optimum conditions of welding variables in the FSW of Al 6061 alloy. Tools of shoulder diameter of 9, 12, 15 mm and pin length of 1.5 mm were used. Also the material's dimension for welding were $2{\times}100{\times}150mm$, and the tensile specimens were worked by water-jet technique. Welding variables were shoulder diameter, rotating speed and travel speed of tool. From the results of this work, the welding factor influenced on yield strength most was travel speed and the optimum condition for FSW was predicted as the shoulder diameter of 15 mm, welding speed of 500 mm/min and rotating speed of 2,000 rpm. Also the presumption range of yield strength at optimal condition of reliability 99% was estimated to $207.19{\pm}9.91MPa$.

• 한국공작기계학회논문집
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• 제16권3호
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• pp.109-116
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• 2007

The present study examined mechanical properties according to the change of outer circumference in the friction welding of A2024-T4 stock, which is used much as aircraft structure, truck wheel, stainless materials and A2024-T4 stock with 10 hollow at the center. Welding conditions were fixed at RPM 2,000rpm, friction pressure of 50MPa, friction time of 1.5sec, upset pressure of 120MPa and upset time of 2.0 seconds. From the result of this study were drawn conclusions as follows : According to the result of a tensile strength test, the solid shaft showed linear increase of tensile strength with the change of outer circumference, the hollow shaft showed maximum tensile stength when the length (L) was 2mm and decrease of tensile strength with the change of outer circumference, hardness appeared to increase and then decrease for welding interface, and it showed maximum hardness 155Hv at L=5mm of the solid shaft. Bending strength increased linearly far change of the distance (L) of outer circumference in the solid shaft and then decreased linearly in the hollow shaft. the result of examining tissue, the tissue grew finer around the welding interface and divided the basic material and the welding surface.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.181-186
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• 2002

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows: optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4kW Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. Laser welding has found a place on Hyundai's production plant in conjunction with the startup of mass production of new sports car, and this production system is the result of a collaboration of its engineers. Outer side sheets are joined to inner side sheets by 122 stitch welds totally. And the length is about 2.4meter.

• 동력기계공학회지
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• 제19권4호
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• pp.11-16
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• 2015

Welding is very popular method for joining two or more metals. In this paper, the three-way factorial design was adopted for obtaining the optimum friction stir welding conditions of Al 5052 alloy. Tools of shoulder diameter of 9, 12, 15 mm and pin length of 1.5 mm were used. Also the material's dimension for welding was $100{\times}100{\times}2mm$, and the tensile specimens were worked by water-jet technique. Welding variables were shoulder diameter, rotating speed of tool and welding speed. As far as this work is concerned, optimum condition for friction stir joint of Al 5052 alloy was predicted as the shoulder diameter of 15 mm, welding speed of 500mm/min and rotating speed of 1000 rpm. In addition, the presumed range of tensile strength under the optimal conditions is estimated to be $208.3{\pm}5.7$ MPa with 99% reliability.

• Journal of Welding and Joining
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• 제20권3호
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• pp.109-115
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• 2002

In this study high power Nd:YAG laser welding of structural steel was investigated. For the test steel blocks of $50{\times}50{\times}200mm$ were cut and machined, and bead-on-plate weld was made on the machined surface. Argon, nitrogen, helium, dry air or mixed gases were used to find the effect of shielding conditions on the bead formation. Results demonstrated that there were Fe I rich region and Fe II rich region in the laser induced plasma column based on the spectral analysis with S-2000 field spectrometer The Fe I region was located at the root of the column near keyhole opening. On the other hand, Fe II region was found at the middle of the plasma column. In the Nd:YAG laser welding, Fe I region emitted continuum which had peak value at wave length of around 710nm, and Fe II region had the peak at 580nm. In the welding of steel by $CO_2$ laser, however, no continuum was observed. There showed two groups of strong spikes in the $CO_2$ laser welding; the first group was displayed at the wave band of 450-560nm. This spike group emitted stronger intensity of light and sharper peaks than those group at 680-800nm.

• Journal of Magnetics
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• 제21권3호
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• pp.374-378
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• 2016

The transformer used in an inverter type arc welding machine is designed to use high frequency in order to reduce its size and cost. Also, selecting core materials that fit frequency is important because core loss increases in a high frequency band. An inrush current can occur in the primary coil of transformer during arc welding and this inrush current can cause IGBT, the switching element, to burn out. The transformer design was carried out in $A_P$ method and amorphous core was used to reduce the size of transformer. In addition, sheet coil was used for primary winding and secondary winding coil considering the skin effect. This paper designed the transformer core with an air gap to prevent IGBT burnout due to the inrush current during welding and proposed the optimum air gap length.

• 한국생산제조학회지
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• 제20권5호
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• pp.570-575
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• 2011

Ultrasonic metal welder is consisted of power supply, transducer, booster, and horn. Precise designing is required since each parts' shape, length and mass can affect driving frequency and vibration mode. This paper analyzed Cu sheet deposition characteristics using ultrasonic metal welder and tension tester. A horn suitable for 40,000Hz was attached to the ultrasonic metal welder in order to weld Cu plates. The Cu sheet welding was done with different amplitude, pressure, and welding time, and its maximum tension was measured with tension tester. Maximum tension of 153.87N was obtained when the pressure was 2.0bar, amplitude was 80%, and welding time was 0.30s. Therefore, excessive welding condition negatively influences maximum tension measurement result.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2053-2058
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• 2008

Extruded aluminium panels have been widely used for railway vehicle structures because of their light specific weight and other merit. In the past, GMAW (Gas Metal Arc Welding) and GTAW (Gas Tungsten Arc Welding) were mainly used to join aluminium panels. But recently friction stir welding (FSW) is widely used. due to its lots of advantage. In this study aluminium A6005-T6 which are used for car body structures was chosen. The influence of main parameters such as : pin rotating speed, welding speed, shoulder diameter, pin length and tilting angle on mechanical properties was examined. Optical microscope observation, micro hardness test and tensile test were carried out. Tensile strength of the stir welded plates is 74% of that of the base material.

• 한국생산제조학회지
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• 제20권3호
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• pp.263-267
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• 2011

Ultrasonic metal welding can be used to weld different metals together safely and precisely, without solder, flux and special preparation. Ultrasonic metal welding machine consists of a power supply, a transducer, a booster and a horn. This paper designed the horn needed for Ultrasonic metal welding. The horn has to be designed and manufactured accurately, because measurements such as the shape, length, mass and etc. have effects on the resonant frequency and the vibration mode. The designed horn has the feature of 40,000Hz of nature frequency, and maximizes vibration range in the Tip by resonance in the frequency of ultrasonic wave machine. In this paper, we calculated and analyzed the natural frequency to find the optimal design of the horn that had the amplitude about $12{\mu}m$ by the modal analysis and harmonic analysis using ANSYS. And we analyzed FFT analysis of the manufactured horn.

• 한국산업융합학회 논문집
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• 제14권2호
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• pp.59-65
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• 2011

$CO_2$ Welding which uses $CO_2$ instead of inert gas is most widely used in industrial sites. Welding rod for $CO_2$ Welding is roughly divided into solid wire and flux cored wire. $CO_2$ Welding has higher efficiency than any other welding methods, and also economic and speedy to handle, that's why is used frequently for welding general structures. As most of studies about $CO_2$ Welding are focused on metallurgical changes of successful joints, they developed theories about the change of configuration on weld parts. This study is especially focused on not only the change of configuration on weld parts, but also the change of the penetrating depth through changing the position of welding torch. For inspection, applied AWS A5.20 E70-1 among welding wires and fixed moving angles of torch, but controled the values of voltage and the position of welding. Also Automatic Feed Mechanism is used for exact movement of material, specimen is a piece of steel for general structures. By measuring and analyzing the configuration of sliced section and the values of welding leg length and welding throat after welding, the outcome about the changes turned out.