• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1369-1375
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• 2004

For many years and primarily for economical reasons, Dissimilar Metal Welds have been used as transition joints in a variety of equipment and applications. But Dissimilar Metal Welds have several fabrication and metallurgical drawbacks that can often lead to in-service failures. For example, the most pronounced fabrication faults are hot cracks. Laser welding techniques have been characterised for various materials. In this paper, the laser weldability of STS304 stainless steel and SM45C at dissimilar metal welds using a continuous wave Nd：YAG laser are experimentally investigated. An experimental study was conducted to determine effects of welding parameters, on eliminating or reducing the extent welding zone formation at dissimilar metal welds and to optimize those parameters that have the most influence parameters such as focus length, power, beam speed, shielding gas, and wave length of laser were tested

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.74-77
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• 2000

Porthole die extrusion has a great advantage in the forming of hollow section tubes difficult to produce by conventional extrusion with a mandrel on the stem. Because of the complicated structure of die assembly, extrusion process as a forming of hollow section tubes has been investigated experimentally Therefore, analytic approaches that are useful in profitable die design and in the improvement of productivity are inevitably demanded Welding strength is affected by many parameters, which are such as extrusion ratio, extrusion speed, die shape, porthole number, bearing length, billet temperature and mandrel shape. In this paper, the parameters, which are such as billet temperature, bearing length and tube thickness, are examined. The welding pressures are examined through 3D simulation of non steady state and compared with experimental results.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.304-306
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• 2006

Positioning the workpiece accurately and preventing the weld distortion, tack welding is often performed before main welding in the construction of welded structures. The weld bead size of the tack weld is determined according to the workpiece thickness, weld length, weld joint type etc. However, this tack weld deteriorates the final weld bead profile, so that the grinding process is usually adopted for the uniform weld bead profile. In this study, an experimental method for the selection of optimal welding condition was proposed in the fillet weld which was done over the tack weld. This method uses the response surface analysis in which the leg length and the reinforcement height of weld bead were chosen as the quality variables of weld bead profile. The overall desirability function, which was combined desirability function for the two quality variables, was used as the objective function for getting the optimal welding condition. From the result, it was revealed that a uniform weld bead can be obtained by adopting the optimal welding condition which was determined according to the method proposed.

• Journal of Welding and Joining
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• 제26권2호
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• pp.92-97
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• 2008

In welding of thin plate, some defects such as melt through and unmelted zone occur easily at welding start, however there is a limited study on those problems. Therefore the effects of start block and arc length on melt through and unmelted zone at start were investigated in this study. When start block height was lower than base metal, there was melt through at start. And when the height was even with base metal, no unmelted zone existed. Unmelted zone was increased as start block height increased from 0mm to 0.5mm. However unmelted zone was not much changed as the height increasing from 0.5mm to 1.0mm. When gap existed between start block and base metal, melt through occurred. However, unmelted zone was increased as the contact force of start block on base metal was increased from 0kgf to 7.5kgf. And when arc length was decreased from 3.8mm to 3.0mm, unmelted zone was decreased. It was concluded that the optimum condition to prevent melt through and to minimize unmelted zone would be with start block height 0.25mm, contact force 3.0kgf, and arc length 3.4mm. This optimum condition was applied to the mass production line and resulted in satisfied outcome.

• Journal of Welding and Joining
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• 제34권1호
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• pp.54-58
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• 2016

In this research paper, suggest method of generate same bead as an actual measurement data in virtual welding conditions, exploit morphology information of the bead that acquired through robot welding. It has many multiple risk factors to Beginners welding training, by we make possible to train welding in virtual reality, we can reduce welding training risk and welding material to exploit bead visualization algorithm that we suggest so it will be expected to achieve educational, environmental and economical effect. The proposed method is acquire data to each case performing robot welding by set the voltage, current, working angle, process angle, speed and arc length of welding condition value. As Welding condition value is most important thing in decide bead form, we would selected one of baseline each item and then acquired metal followed another factors change. Welding type is FCAW, SMAW and TIG. When welding trainee perform the training, it's difficult to save all of changed information into database likewise working angle, process angle, speed and arc length. So not saving data into database are applying the method to infer the form of bead using a neural network algorithm. The way of bead's visualization is applying the spline algorithm. To accurately represent Morphological information of the bead, requires much of morphological information, so it can occur problem to save into database that is why we using the spline algorithm. By applying the spline algorithm, it can make simplified data and generate accurate bead shape. Through the research paper, the shape of bead generated by the virtual reality was able to improve the accuracy when compared using the form of bead generated by the robot welding to using the morphological information of the bead generated through the robot welding. By express the accurate shape of bead and so can reduce the difference of the actual welding training and virtual welding, it was confirmed that it can be performed safety and high effective virtual welding education.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.189-194
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• 2007

최근 자동차 안전에 대한 수요자의 요구가 증대되면서 용접부에 대한 품질검사방식도 강화되고 있다. 이에 따라 시트구조물의 용접부 비드 형상치수를 육안검사 또는 수동검사에 의존하던 방식에서 전수기록검사에 의한 품질관리가 요구되고 있다. 본 연구에서는 시트프레임 용접부의 품질검사를 위하여 작업자가 용접비드를 측정하면 자동으로 계측되는 시스템을 LabVIEW를 이용하여 개발하였다. 용접부의 비드 폭과 길이에 대한 품질 기준을 입력하여 놓으면 측정 시 측정하고자 하는 대상이 비드길이 인지 폭인지를 자동으로 판단하여 측정되도록 하였으며 측정된 데이터는 포인트별로 저장 기록되어 용접부의 품질기록을 보존토록 하였다. 이러한 시스템을 자동차 시트 용접부에 적용하여 실험하였으며 품질관리 작업효율에 좋은 영향을 주었다.

• 한국해양공학회지
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• 제27권5호
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• pp.77-81
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• 2013

The effects of the welding parameters, contact tip-to-workpiece distance (CTWD), current, and voltage on the diffusible hydrogen content in weld metal deposited by self-shielded flux cored arc welding were investigated and rationalized by comparing the amount of heat generated in the extension length of the wire. This showed that as CTWD increased from 15mm to 25mm, the amount of heat generated was increased from 71.1J to 174.8J, and the hydrogen content was decreased from 11.3mL/100g to 5.9mL/100 g. Even if little difference was observed in the amount of heat generated, the hydrogen content was increased with an increase in voltage because of the longer arc length. A regression analysis showed that the regression coefficient of voltage in self-shielded flux cored arc welding is greater than that in $CO_2$ arc welding. This implies that voltage control is more important in self-shielded flux cored arc welding than in $CO_2$ arc welding.

• 한국정밀공학회지
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• 제20권5호
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• pp.66-72
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• 한국기계가공학회지
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• 제11권1호
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• pp.76-81
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• 2012

Ultrasonic metal welding is one of the welding methods which welds metal by applying high frequency vibrational energy into specific area at constant pressure, avaliable in room temperature and low temperature. 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 focused to horn design, its length L was set to 62mm by calculating vibration equation. By performing modal analysis with various shape variable b times integer, when length of b is 30mm the output was 39,599Hz at 10th mode. Also by performing harmonic response analysis, the frequency response result was 39,533Hz, which was similar to modal analysis result. In order to observe the designed horn's performance, about 4,000 voltage data was obtained from a light sensor and was analyzed by FFT analysis using Origin Tool. The result RMS amplitude was approximately 8.5${\mu}m$ at 40,000Hz, and maximum amplitude was 12.3${\mu}m$. Therefore, it was verified that the ultrasonic metal welding horn was optimally designed.

• Journal of Welding and Joining
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• 제14권5호
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• pp.113-121
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• 1996

The arc sensor has been most widely used for weld seam tracking through welding current or voltage variation. In this work, the relation between the arc light intensity and welding condition is investigated using heat balance in the Plasma for its possible application to seam tracking in the GMAW process. The arc light intensity is derived to be the function of the arc length and welding current Experiments are carried out to verify the proposed heat balance model. Performances of least square and integration methods to process the signals for seam tracking are compared experimentally. Predicted arc light intensity shows reasonably good agreement with experimental results. The weld seam is successfully tracked through the arc light intensity. The least square and integration methods demonstrate almost same performance of seam tracking with $CO_2$gas shielding.