• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.53-56
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• 2007

Magnesium sheet used in electrical device due to mobility and EMF shielding characteristics. Magnesium case by press forming was advantageous compare with conventional die casting process, because of its thin gauge of wall and surface quality. But it need to makes the boss to fix inner part or assemble the case. CD stud welding was effective way for joining the boss to the thin gauge case of the electrical devices. In this study, we investigated the performances of the magnesium boss welder To measure the process parameters such as the force and the weld current, we design the monitoring system for CD stud welding. We test the characteristics of CD stud welding for AZ31 sheets at some variables. Finally we select the optimum welding range of magnesium sheets in CD stud welding process.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.283-287
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• 2004

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving a ship. In this case cola arc welding. is good for. saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI. happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's repair working shop.

• 한국해양공학회지
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• 제20권2호
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• pp.41-45
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• 2006

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving n ship. In this case cold arc welding is good for saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's working shop.

• 플랜트 저널
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• 제4권2호
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• pp.66-72
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• 2008

In this inquiry, I would suggest jet ventilation system for effective elimination of welding flaw at machinery material welding shop on plant and evaluate the airstream on inner space and property of welding flaw's density through the examination. We can know outer atmosphere inflows at the speed of about 0.05m/s from western entrance in case of stopping the jet ventilation system, but airstream is accumulated on entire space. At height of worker's breathing surface(Ground Level = 1.5 m, below of GL) and welding work center, density of welding flaw on upper part(GL = 12m) is appeared 4 times higher than outer atmosphere at surplus range besides nearby of western entrance. At operation of jet ventilation system, since the smooth air current transfer at inner space and exhaust effect the wind speed is maintained at 0.932 m/s at the point of height of worker's breathing surface on inner space and it's concluded about the working conditions have been better than before operation of jet ventilation system because of that results show that inner space density of welding flaw at height of worker's breathing surface is 40.5%, and in the work shop, it is 20.3% at upper part.

• 한국산학기술학회논문지
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• 제8권1호
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• pp.96-102
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• 2007

용접에 의해서 발생하는 변형은 강구조물의 치수를 변화시킬 뿐 아니라 역학적 강도를 저하시켜 강구조물의 제작공정과 공용중 심각한 문제를 발생시킬 수 있다. 특히 토목 강구조물의 경우 제작 및 조립공정에서 용접프로세스에 의해 불가피하게 발생하는 용접변형에 의한 설계치수의 변화를 검토하기 위해 넓은 장소에서 부분 또는 전체가 조립공정을 실시해야 한다. 이러한 가조립된 구조물은 현장에 설치되기 위해 해체하여 운반되어 현장에서 재조립하여 가설된다. 또한 높은 곳에서 작업해야 하므로 안전사고의 우려와 함께 크레인, 족장과 같은 부대장비를 사용해야 하므로 비경제적이다. 따라서 대형 강구조물의 제작시 발생하는 용접변형에 의한 부재오차를 검증하기 위한 가조립 공정을 생략하기 위해 용접변형 예측기법의 개발이 요구된다. 본 연구에서는 이를 위해 대형 강구조물의 용접변형 예측기법인 등가하중법을 이용한 용접부 수치모델링을 정립하고 이를 이용해 용접순서와 자중이 용접변형에 미치는 영향을 검토하였다.

• Journal of Welding and Joining
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• 제30권3호
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• pp.66-70
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body is spot welding. And $CO_2$ arc welding is used in a small part. In production field, $CO_2$ arc welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ arc welding process frequently. But $CO_2$ arc welding process should be used at robot interference parts and closed parts where spot welding couldn't. $CO_2$ welding is divided into lap welding and plug arc spot welding. In case of plug arc spot welding, burn through and under fill were caused in various welding environment such as different thickness combinations of base metal, teaching point, over the two steps welding and inconsistent voltage/current. It makes some problem like poor quality of welding area and decrease the productivity. In this study, we will evaluate the effect of teaching point through the weld pool behavior and bead geometry in the arc spot welding at the plut hole. Welding position is horizontal position. And galvanized steel sheet of 2.0mm thickness that has plug hole of 6mm diameter was used. Teaching point was changed by center, top, bottom, left and right of the plug hole. At each condition, the phenomenon of weld pool behavior was confirmed using a high-speed camera. As the result, we find the center of plug hole is the most optimal teaching point. In the other teaching point, under fill was occurred at the plug hole. This phenomenon is caused by gravity and surface tension. For performance of arc spot welding at the plug hole, the teaching condition should be controlled at a center of plug hole.

• 한국생산제조학회지
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• 제20권6호
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• pp.679-684
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• 2011

Recently, STS 301L joints of side panels to frames for stainless steel rolling stock have been made out by using existing welding methods including Resistance Spot Welding, Laser Welding and Arc Welding. Most of the processes were jointed by spot welding because it is faster at welding and comparatively less expensive for investment in welding facilities than other methods. During spot welding, however, indentation of the metal surface was made due to pressure and melting property of welding. Moreover, since the melting metal was forced to periphery of the plate as indentation was made, sheet separation, which cracked apart between jointed sheets, was carried out. A slight deformation which resulted from sheet separation deteriorated the emotional quality of railway vehicles. This paper suggests that by processing conventional spot electrode tip appropriately, melting metal is able to push up around the processed part (Hollow Spot Electrode Tip) and prevent from being dislodged from first place to periphery. Consequently, sheet separation is remarkably decreased. Also, the emotional quality of appearance of stainless steel rolling stock is enhanced considerably.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.17-18
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• 2006

Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is 1400W of the laser power, 0.8m/min, 0.9m/min of welding speed and $4{\ell}$ in of pressure for shielding gas.

• 한국기계가공학회지
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• 제5권4호
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• pp.65-71
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• 2006

The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part on current industries. In this study, it is investigated about endurance and fatigue crack propagation rate of according to welding methods such as SMAW, FCAW and SAW commonly used for welding structures in present. Endurance limits carried out highly in the order of SMAW, FCAW, SAW and fatigue crack propagation rate out lowly in the order of SMAW, FCAW, SAW. By these results, it is needed to use SMAW welding method for welding structures with small welding capacity and FCAW, SAW methods for large welding structures after consideration about economic gains and operation efficiency of welding. Fatigue crack propagation rate is more affected by strength of welding materials than endurance limit of welding materials according to welding methods.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.219-226
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• 2017

These days, the great part of design processes in the field of ship or offshore manufacturing are planned and implemented using the CAD system customized for shipbuilding companies. It means that all information for design and production could be extracted and reused at the other useful fields which need cost considerable time and efforts. The typical example is the field of welding material quantity evaluation which is demanded during the construction of ship or offshore structures. The proper evaluation of welding material to be used and the usage of them at the stage of schedule planning are mostly important to achieve the seamless process of production and costing in advance. This study is related to the calculation of welding length and needed welding material quantity at the stage of design completion utilizing the customized CAD system. The calculated welding material quantity would be classified according to welding posture, assembly stage, block, bevel and welding type so as to improve the accuracy of total cost evaluation. Moreover it is possible to predict the working time for welding operation and could be used efficiently for the cost management using the results of this research.