The demand for LNG Carrier and LNG fuel ships are increasing due to global carbon neutrality declaration and ship emissions regulation of IMO, domestic shipyards pay technology fees(about 5~10% of ship price per vessel) to GTT company in France for making LNG cargo hold. Localization of LNG cargo hold is needed to reduce technology fees and engage technological competitiveness, it is important to secure the critical technology like automation process development of insulation system process. Especially, the automation rate of membrane-type insulation system is very low due to interference caused by corrugation and difficulty in securing optimal variable welding condition. In this study, to solve this problem, automatic welding is performed using developed automatic welding equipment on STS304L steel which is used in flat and corner area of membrane-type LNG cargo hold's lap joint. After welding, Cross-sectional observations and Tensile strength tests were conducted to evaluate reliability of equipment and welding condition. As a result of the test, it was confirmed that the strength of the welded zone exceeded that of base material, and secured the optimal welding condition to apply automatic welding.

In this study, the structural analysis and welding performance experiments were performed to reduce the weight of the semi-automatic TIG welding device. The structural analysis based on finite element method was performed on the lightweight design of the wire feeder's main frame to evaluate the structural safety and straightness of the lightweight frame. To reduce the weight of the welding wire feeder, the step motor was changed to a servo motor and a pinion gear made of lightweight reinforced plastic material was applied. In addition, a new type of welding torch was developed to reduce the weight of the welding torch and to supply more effective fillers. As a result of performing the TIG welding experiment using a prototype of TIG welding device consisting of a lightweight frame, feeding device and welding torch, it was confirmed that the working criteria were satisfied in terms of welding speed, welding bead shape, feeding uniformity and torch durability. The developed lightweight TIG welding device is expected to improve welding productivity and work convenience.

This study introduces the web-camera image processing-based natural landmark extraction method for automatic welding using 3-axis stage. The welding is a highly significant process in the industries of shipbuilding, automobile, construction, machinery, and so on. However, it has been avoided due to poor working conditions such as fume, spatter, noise, and so on. For the automatic welding system, the web-camera is used to extract the natural landmarks which can give the relative coordinate to set up the initial position of the stage for the welding process. The Canny edge and Hough transformation have been used to extract the significant points for the natural landmark extraction in this paper.

Stress distribution and deformation on the cross tension type spot welded lap joint subjected to out of plane tensile load were investigated by finite element method. For the rational design of spot welded joint, it is needed to assess to repeatedly the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automation of repeated process of fatigue life assessment for spot welded cross tension type joint was studied. The process is related to stress analysis in vicinity of weld-toe and fatigue life assessment based on analyzed stress distribution. With the change of design condition including dimensions and welding heat input, the above two works have to be performed. Using the commercial tool for system integration, ModelCenter, an automation of the repeated process for spot welded cross tension type joint based on 2D modeling was achieved. In this automation system, data exchanges between programs regardless of commercial and parametric studies for optimal design can be performed.

용접은 가장 널리 사용되는 금속접합기술이며 조선, 자동차, 항공, 플랜트설비 등 산업현장의 여러 분야에서 활용되고 있는 근대산업의 기본적인 생산기술이다. 그러나 용접작업 자체가 강한 빛과 전류, 유해가스등을 발생하고 있으며, 다품종 소량 생산하는 작업장에서는 규격화된 물건을 만들어 내는 제조업에 비해서 자동화가 어렵다. 따라서 범용적으로 모든 형태의 용접할 부위인 용접선을 검출하여 자동으로 용접하기란 상당히 어려우며, 본 논문에서는 삼각파 형태의 굴곡을 가진 용접선을 검출하고자 스트레인게이지를 응용한 센서를 이용하였고, 이를 직선구동이 가능한 반자동 캐리지에 탑재하여 용접선을 자동으로 추적하여 용접하는 실험을 제안하였다. 캐리지는 직선 전진만 하고 있더라도 굴곡이 있는 용접선을 자동으로 검출하여 용접이 가능하도록 하였다.