• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.246-254
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• 2016

Thick-shell welding for super-sized oil storage tanks is currently done manually, which causes deterioration in quality and a lack of uniformity due to frequent rewelding. The limitations of the external environment must also be considered for manual welding. This paper describes the development of a carriage system for automatic vertical welding to increase reliability, reduce cost, and enhance productivity. The system consists of a welding platform, carriage device, and control unit, which were conceptually designed according to design specifications and manufactured with modular parts. In addition, the structure was analyzed for safety and to predict design problems in advance, and the results are reflected in reviewing the design. To evaluate the performance of the system, a tensile test, bending test, and weld time test were carried out, and the results were satisfactory. The time required for automatic weld was greatly improved by more than 87%, compared to the manual welding time.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.230-237
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• 2015

To improve productivity and improve the welding process, we have studied the automated system of the weld by applying a tandem welding. Then, the speed of the welding process is improved, production of industries is increasing. Productivity of the industrial sector has increased the application of tandem welding for automated system of welding. But quality assurance for the product take place welding defects in the welding process because the speed of the process is increased. Definitive research solutions an dit's actuality, however, there is insufficient. Accordingly, it is a situation that the performance of the weld to ensure quality of the weld is required urgently after the welding process. Comparing and analyzing the results of passing each experiment of the two-electrode welding and the welding electrode1, a study attempted to quality assurance of the welded joint portion.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.297-299
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• 2007

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.45-47
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• 2007

주강소재 보수용접부의 품질 및 용접생산성 향상을 위해 기존 용접후열처리 조건(이하 PWHT)을 모재에 적용하는 품질열처리(이하 NTT)로의 대체 및 반자동 FCAW 용접방법의 적용 가능성을 확인하기 위해 상온 및 고온 물성평가(고온인장강도, 크리프 파단강도)를 수행한 결과, 제작 공정 측면에서 FCAW의 적용이 가능한 것으로 확인되었다. 또한 PWHT 대신 NTT를 적용함으로서 용접방법별 물성 편차가 줄어드는 NTT 열처리의 긍정적 효과가 확인되어, 궁극적으로 기존 PWHT 및 NTT 모두 적용이 가능한 것으로 확인되었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.985-993
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• 2001

Neural networks are shown to be effective in being able to distinguish incomplete penetration-like weld defects by directly analyzing the plasma which is generated on each impingement of the laser on the materials. The performance is similar to that of existing methods based on extracted feature parameters. In each case around 93% of the defects in a database derived from 100 artificially produced defects of known types can be placed into one of two classes: incomplete penetration and bubbling. The present method based on classification using plasma is faster, and the speed is sufficient to allow on-line classification during data collection.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.88-93
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• 1999

This paper presents the experimental examinations and statistical quantitative analysis of the correlation between the cumulative counts of acoustic emission(AE) during plastic deformation periods of the welding and the tensile strength and other properties of the bar-to-bar welded joints of O.D. 16mm shaft(SM40C) as well as the various welding variables. And this is a new approach which attempts finally to develop real-time quality monitoring system for friction welding. The results lead to a practical possibility of real-time quality control more than 100% joint efficiency showing good weld with no micro structural defects.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.628-631
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• 2010

환경문제에 대한 관심으로 자동차에 대한 경량화가 요구되는 동시에 안전규제가 강화 되고 있어, 높은 인장강도를 가지는 고강도 강의 차체 적용 비율이 점차 증가하고 있다. 또한, 자동차 1대를 조립하기 위한 저항 점용접 횟수를 줄이고, 용접부에 충격안정성을 확보하기 위한 관심이 고조되고 있다. 따라서, 국내 자동차 산업에서 용접부의 신뢰성을 보장하기 다양한 비파괴 검사를 적용하고 있으며, 생산 공정에 적용하고 있다. 그중에서 용접 전극 사이에서 동저항(Dynamic resistance, 용접 공정중모재의 저항값의 변화)을 계측하여 용접성을 평가하는 방법이 제시되고, 차체 조립공정 중에 적용하려는 시도가 이루어지고 있다. 본 연구에서는 자동차 차체용 냉간 압연강판(590MPa dual-phase steel)을 인버터 DC 저항 점 용접하여, 용접전극 사이에서 동저항을 측정 하였다. 용접성은 인장전단 강도로 평가하였고, 용접 공정 변수는 용접 전류, 용접 시간, 가압력을 선정하였다. 동저항 그래프의 ${\alpha}$-peak와 ${\beta}$-peak값을 인장전단 강도에 따라 회귀 분석하여, 동저항에 따른 인장전단 강도를 예측하였다. 추가적으로, 용접부의 외관 형상 중에 압흔 깊이와 압흔자국 지름에 대한 회귀분석을 실시하였으며, 용접부 형상에 대한 신뢰성을 부여하였다.

• Journal of the KSME
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• v.33 no.5
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• pp.435-448
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• 1993

용접부결함은 구조물 건전성측면에서 항상 문제가 되어 왔다. 따라서 용접시 발생 할 수 있는 결함들을 사전에 방지하기 위한 대책들이 꾸준히 연구되어 왔으며, 용접부의 최종 품질확인 및 부품 사용중 용접부의 건전성을 평가하기 위한 수단으로 비파괴시험법들이 오래전부터 적용되어 왔다. 따라서 이 글에서는 용접부의 특성, 용접부결함의 중요성에 대해 기술하고 부품 건전성의 진단목적으로 결함의 유무 및 크기측정을 위해 사용되는 비파괴시험법의 종류 및 특징, 비파괴 시험법 중에서 결함의 길이 및 두께방향의 높이측정을 위해 유일하게 이용되는 초음파시험법에 대해, 특히 결함크기 측정법 중 현재 널리 사용되는 몇 가지 방법에 대해 소개하고자 한다.

• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.83-91
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• 1999

Taking a view of joining by welding the IN713C to SCM440 and SCM415 steel in production of turbochargers, the frictin welding process may be utilized as a new approach for joining them of other conventional welding processes. It is because the friction welding has more technical and technical and economic advantages than the other welding processes. As this welding process has the characteristics such as curtaliment of production time and materials and cost reduction, etc.. So, this paper deals with determining the preper friction welding condition and analyzing various mechanical properties of friction welded joints of the super heat resisting steel to alloy stee(IN713C to SCM440 and SCM415). And the in-process real-time weld quality evaluation technique by acoustic emission during friction welding of IN713C to SCM440 and SCM415 steels with higher confidence and relibility has been much required even though it might be the first trial approach for developing it. Then, this first study aimed to develop the optimization of dissimilar friction welding of heat resisting steels (INC713 to SCM440, SCM415) for turbine, considering on strength and toughness.

• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.2
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• pp.112-121
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• 1994

This paper discusses the feasibility of ultrasonic C-scan technique for nondestructive evaluation of spot weld quality. Ultrasonic evaluation for spot weld quality was performed by immersion method with the mechanical and the electronic scanning of point-focussed ultrasonic beam(25 MHz). For the sake of the approach to the quantitative measurement of nugget diameter and the discrimination of the corona bond from nugget, preliminary infinitesimal gap experiment by newton ring is tried in order to set up the optimum ultrasonic test condition. Ultrasonic image data obtained were confirmed and compared by optical microscope and SAM(Scanning Acoustic Microscope) observation of the spot-weld cross section. The results show that the nugget diameter can be measured with the accuracy of 1.0mm, and voids included in nugget can be detected to $10{\mu}m$ extent with simplicity and accuracy. Finally, it was found that it is necessary to make a profound study of definite discrimination of corona bond from nugget and the approach of quantitative evaluation of nugget diameter by utilizing the various image processing techniques.