• 한국공작기계학회논문집
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• 제13권5호
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• pp.110-117
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• 2004

In automatic welding process using a robot, seam tracking is one of the important parts. Sensor for seam tracking is divided broadly into two categories as non contact sensor and contact sensor. The arc sensor is one of the non contact sensors, and it can be applied in weaving arc and rotating arc welding process. In such the arc sensors, rotating arc sensor can be applied to high speed welding over tens of Hz. The decrease of self regulation by high rotating speed causes to improve accuracy and response of sensor. In this study, fuzzy controller was used to track the seam for the $CO_2$ arc welding which had unstable arc. It could be shown that the rotating arc sensor was better than the weaving arc sensor.

• 한국생산제조학회지
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• 제23권6호
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• pp.602-608
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• 2014

Mixed-model production lines are often used in manufacturing systems. In production lines, different product types are simultaneously manufactured by processing small batches. This paper describes a new welding assembly technology involving the development of experimental models for a mixed-model production line in an automobile company. Due to the extensive number of models, the design of a welding assembly system is complicated. Performance evaluation is an important phase in the design of welding assembly lines in a mixed-model production environment. In this study, a new welding assembly technology for a mixed-model production method was used to weld the package tray and dash panel of a vehicle.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.706-713
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• 2002

In the multi-pass welding of pressure vessels or ships, the mechanical touch sensor system is generally used together with a manipulator to measure the gap and depth of the narrow gap to perform seam tracking. Unfortunately, such mechanical touch sensors may commit measuring errors caused by the eterioration of the measuring device. An automation system of narrow gap multi-pass welding using a laser vision system which can track the seam line of narrow gap and which can control welding power has been developed. The joint profile of the narrow gap, with 250mm depth and 28mm width, can be captured by laser vision camera. The image is then processed for defining tracking positions of the torch during welding. Then, the real-time correction of lateral and vertical position of the torch can be done by the laser vision system. The adaptive control of welding conditions like welding Currents and welding speeds, can also be performed by the laser vision system, which cannot be done by conventional mechanical touch systems. The developed automation system will be adopted to reduce the idle time of welders, which happens frequently in conventional long welding processes, and to improve the reliability of the weld quality as well.

• 국제초고층학회논문집
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• 제11권2호
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• pp.115-124
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• 2022

Welding is a significant part of the construction industry. Since most high-rise building construction structures rely on a robust metal frame welded together, welding defect can damage welded structures and is critical to safety and quality. Despite its importance and heavy usage in construction, the labor shortage of welders has been a continuous challenge to the construction industry. To deal with the labor shortage, the ultimate goal of this study is to design and develop an automated robotic welding system composed of a welding machine, unmanned ground vehicle (UGV), robotic arm, and visual sensors. This paper proposes and focuses on automated weaving using the robotic arm. For automated welding operation, a microcontroller is used to control the switch and is added to a welding torch by physically modifying the hardware. Varying weave patterns are mathematically programmed. The automated weaving is tested using a brush pen and a ballpoint pen to clearly see the patterns and detect any changes in vertical forces by the arm during weaving. The results show that the weave patterns have sufficiently high consistency and precision to be used in the actual welding. Lastly, actual welding was performed, and the results are presented.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.3-3
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• 2009

선박의 건조과정에서 필수적으로 선체 외판에는 선박의 안전과 운항 및 정비 등에 필요한 정보를 나타내기 위해 다양한 종류의 마크 및 문자가 마킹되어진다. 하지만, 단순한 도장 작업만으로는 해상과 같은 부식 환경에서 마크 및 문자가 쉽게 지워지거나 손상되기 때문에 마크 및 문자를 용접 비드(welding bead)로 표시하거나 미리 절단된 강판(steel plate)을 수동으로 용접한 뒤 도장을 함으로써 마크 및 문자의 손상을 방지하고 있다. 이러한 문자마킹작업을 하기 위해서는 작업자가 수작업으로 기준선과 마크 및 문자의 위치를 먹줄 등을 이용하여 마킹을 하고, 해당 마크 및 문자의 템플렛(template)을 이용하여 펀칭을 실시한 후 수동으로 용접을 실시한다. 하지만, 수작업을 통한 선체외판 문자마킹 작업은 작업자의 기량에 따라 품질이 상이하여 품질 저하의 원인이 된다. 또한 대조립 및 탑재 단계에서 문자 마킹 작업시 수직자세의 용접을 요구함으로써 작업자가 안전사고에 노출되어 있으며, 선박의 각 단계별 주요 공정보다 작업시간이 길어져 전체 선박 건조공정을 지연시키는 문제점 등을 야기시킬 수 있다. 이러한 문제점들을 해결하기 위해 조선업계에서는 선체 외판의 마크 및 문자를 자동으로 용접할 수 있는 장치를 개발하기 위해 노력해왔으며, 몇몇 개발 사례가 보고되고 있다. 하지만, 그 실효성 부분에서는 아직까지 해결하지 못한 문제점들로 인해 현장 적용에는 어려움을 보이고 있다. 본 연구에서는 선박외판 문자 자동용접장치의 기능성뿐만 아니라 현업 적용성을 가장 우선적으로 고려하여 문자마킹장치(Marking Robot for Shipbuilding) 개발을 진행하였다. 우선, 적절한 용접 재료를 선정하기 위해서 솔리드 와이어(Solid Wire)와 플럭스 코어드 와이어(Flux Cored Wire)에 대한 비드온 용접(Bead-On Welding)을 아래보기자세와 수직자세에 대해서 실시하여 적절한 용접 조건을 설정하였다. 본 연구에서 개발된 문자마킹 자동용접장치는 3축으로 구성되어 있으며 각 축들을 분리할 수 있도록 개발하여 이동성을 향상시켰으며, 작업면과 용접토치간의 거리를 일정하게 유지시킬 수 있도록 용접전류 센서(Welding Current Sensor)를 이용하여 토치 높이(Wire Extension)를 제어함으로써 균일한 품질의 용접비드를 얻을 수 있었다. 또한 문자마킹 자동용접장치는 본체 구동부와 제어부(Touch Screen)가 쉽게 분리되고 장착이 가능한 구조로 개발되었으며, 용접시 각 용접자세별로 용접전압, 전류 그리고 용접속도 설정이 가능하여 아래보기 자세뿐만 아니라 어떠한 자세에서도 같은 모양의 비드형상을 가지는 문자마킹용접이 가능하도록 개발하였으며, 이는 실험과 현장적용을 통해 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.575-581
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• 1993

This paper deals with analysis of articulated robot manipulator used for Arc welding and Material handling. Compared with present robot of which weight holding capacity is 6kg, this robot shows wider and symmetric working range for it's serial type mechanism. The link length is determined to have widest working range by using optimal simulation. To reduce body's weight, small AC servo motor is adopted and driving peak torque exerted at each joint is reduced by using dynamic analysis. So it is possible to reduce body's weight by 40% compared with the same class's robot and get wider working range. And by adopting modular design concept, each axis is designed to be changed easily for user's special need and repair.

• 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.

• Journal of Welding and Joining
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• 제14권6호
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• pp.131-139
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• 1996

The response of the arc sensor using the welding current and/or welding voltage as its outputs has been obtained by the analysis and/or experiments of the static characteristics of arc sensor. But in order to improve the reliability of arc sensor, it is necessary to know its dynamic characteristics. So in this paper, it is presented the dynamic model of arc sensor including the power source, arc voltage, electrode burnoff rate, and wire feed rate. A numerical simulation of the dynamic model of arc sensor was implemented, computing the welding current with input of CTWD. The results of computer simulations and experiments of $CO_2$arc welding showed that a linear relationship between weaving center - weld line distance and current area difference was established. Additionally, a real-time weld seam tracking system interfaced with industrial welding robot was constructed, the result of the weld seam tracking experiment for weld line with an initial offset error of 5$^{\circ}$was good.

• Journal of Welding and Joining
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• 제23권4호
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• pp.41-47
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• 2005

Generally, the use of robots in manufacturing industry has been increased during the past decade. GMA(Gas Metal Arc) welding process is an actively Vowing area, and many new procedures have been developed for use with high strength alloys. One of the basic requirement for the automatic welding applications is to investigate relationships between process parameters and bead geometry. The objective of this paper is to develop a new approach involving the use of neural network and multiple regression methods in the prediction of bead geometry for GMA welding process and to develop an intelligent system that visualize bead geometry in order to employ the robotic GMA welding processes. Examples of the simulation for GMA welding process are supplied to demonstrate and verify the proposed system developed using MATLAB. The developed system could be effectively implemented not oかy for estimating bead geometry, but also employed to monitor and control the bead geometry in real time.

• International Journal of Korean Welding Society
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• 제4권1호
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• pp.30-37
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• 2004

There have been continuous efforts on automating welding processes. This automation process could be said to fall into two categories, weld seam tracking and weld quality evaluation. Recently, the attempts to achieve these two functions simultaneously are on the increase. For the study presented in this paper, a vision sensor is made, a vision system is constructed and using this, the 3 dimensional geometry of the bead is measured on-line. For the application as in welding, which is the characteristic of nonlinear process, a fuzzy controller is designed. And with this, an adaptive control system is proposed which acquires the bead height and the coordinates of the point on the bead along the horizontal fillet joint, performs seam tracking with those data, and also at the same time, controls the bead geometry to a uniform shape. A communication system, which enables the communication with the industrial robot, is designed to control the bead geometry and to track the weld seam. Experiments are made with varied offset angles from the pre-taught weld path, and they showed the adaptive system works favorable results.