• Journal of Welding and Joining
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• 제25권6호
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• pp.44-52
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• 2007

A welding process of a lifting lug for lifting heavy objects is one of the important welding processes directly related to the safety in shipbuilding. Welding a lifting lug is done in the manually and takes about forty minutes. Working environment for the lifting lug welding is very poor due to an radiant heat and a harmful fume. The purpose of this study is to develop methods of multi-pass welding using the lifting lug welding robot system. This study shows robot welding methods to achieve proper corner, straight and connection welding and an effectiveness of application.

• 한국시뮬레이션학회논문지
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• 제22권2호
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• pp.93-100
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• 2013

다품종 소량생산이 보편화 되면서 하나의 생산라인에서 여러 종류의 제품을 교대로 생산하는 혼류생산방식이 보편화 되었다. 하지만 흐름라인 방식의 혼류생산에서는 필연적으로 작업장 간의 공정시간 불균형이 존재한다. 따라서 이러한 공정불균형에 의한 대기의 낭비를 최소화하기 위하여 기존의 흐름생산방식에서 셀생산방식으로 전환하는 시도가 빈번하게 발생한다. 본 논문에서는 굴삭기 부품을 생산하는 혼류흐름라인 방식의 자동화 로봇 용접라인을 FMC 개념의 직선형 셀방식으로 전환하는 과정에서 타당성 검토를 위해 시뮬레이션을 수행한 사례연구 결과를 소개한다. 분석결과 26.7%의 생산량 증가와 55% 이상의 리드타임 감소효과가 예상되었다. 또한 향후 제품 생산비율의 변화에 따른 민감도분석을 수행하였다.

• 제어로봇시스템학회논문지
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• 제13권11호
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• pp.1060-1066
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• 2007

When a high-energy ultrasound propagates through a solid body that contains a crack or a delamination, the two faces of the defect do not ordinarily vibrate in unison, and dissipative phenomena such as friction, rubbing and clapping between the faces will convert some of the vibrational energy to heat. By combining this heating effect with infrared imaging, one can detect a subsurface defect in material efficiently. In this paper a detection of the welding defect of thin SUS 304 plates using the UIR (ultrasonic infrared imaging) technology is described. A low frequency (20kHz) ultrasonic transducer was used to infuse the welded thin SUS 304 plates with a short pulse of sound for 280ms. The ultrasonic source has a maximum power of 2kW. The surface temperature of the area under inspection is imaged by a thermal infrared camera that is coupled to a fast frame grabber in a computer. The hot spots, which are a small area around the defect tip and heated up highly, are observed. From the sequence of the thermosonic images, the location of defective or inhomogeneous regions in the welded thin SUS 304 plates can be detected easily.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.319-324
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• 2001

This paper presents the motion control of a mobile robot with arc sensor for lattice type welding. Its dynamic equation and motion control method for welding speed and seam tracking are described. The motion control is realized in the view of keeping constant welding speed and precise target line even though the robot is driven along a straight line or corner. The mobile robot is modeled based on Lagrange equation under nonholonomic constraints and the model is represented in state space form. The motion control of the mobile robot is separated into three driving motions of straight locomotion, turning locomotion and torch slider controls. For the torch slider control, the proportional integral derivative (PID) control method is used. For the straight locomotion, a concept of decoupling method between input and output is adopted and for the turning locomotion, the turning speed is controlled according to the angular velocity value at each point of the comer with range of $90^{\circ}$ constrained to the welding speed. The experiment has been done to verify the effectiveness of the proposed controllers. These results are shown to fit well by the simulation results.

• 한국산업융합학회 논문집
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• 제25권5호
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• pp.799-810
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• 2022

Welding work is a production work method widely used throughout the industry, and various types of welding technologies exist. In addition, many methods are being studied to automate these welding operations using robots, but in the ship manufacturing field, welding such as painting, cutting, and grinding is also the most common operation, but the manual operation ratio is higher than in other industries. Such a high manual labor ratio in the field of ship manufacturing not only causes quality problems and production delays according to the skill of workers, but also causes problems in the supply and demand of manpower. Therefore, this paper analyzed the reason why the automation rate is low in welding work at ship manufacturing sites compared to other industries, and analyzed the production process and field environment for small and medium-sized ship manufacturing companies that repeatedly manufactured with a small quantity production method. Based on the analysis results, it is intended to propose a robot system that can easily move between workplaces and secure uniform welding quality and productivity by collaborating simple welding tasks with humans. Finally, the simulation environment is constructed and analyzed to secure the suitability of robot system application to current production site environment, work process, and productivity, rather than to develop and apply the proposed robot system. Through such pre-simulation and robot system suitability analysis, it is expected to reduce trial and error that may occur in actual field installation and operation, and to improve the possibility of robot application and positive perception of robot system at ship manufacturing sites.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.776-787
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• 2002

Automation of welding process in shipyards is ultimately necessary, since the welding site is spatially enclosed by floors and girders, and therefore welding operators are exposed to hostile working conditions. To solve this problem, a welding mobile robot that can navigate autonomously within the enclosure has been developed. To achieve the welding task in the closed space, the robotic welding system needs a sensor system for the working environment recognition and the weld seam tracking, and a specially designed environment recognition strategy. In this paper, a three-dimensional laser vision system is developed based on the optical triangulation technology in order to provide robots with 3D work environmental map. Using this sensor system, a spatial filter based on neural network technology is designed for extracting the center of laser stripe, and evaluated in various situations. An environment modeling algorithm structure is proposed and tested, which is composed of the laser scanning module for 3D voxel modeling and the plane reconstruction module for mobile robot localization. Finally, an environmental recognition strategy for welding mobile robot is developed in order to recognize the work environments efficiently. The design of the sensor system, the algorithm for sensing the partially structured environment with plane segments, and the recognition strategy and tactics for sensing the work environment are described and discussed with a series of experiments in detail.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.288-294
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• 2009

The purpose of this study is manufacturing of monolithic housing for modularization of steering gear. Monolithic housing is difficult to weld with only rotation and linear motion. It is for this reason that housing of joining parts have a slope of 76.3 degrees. For this reason, welding trajectory was measured by the cooperative controled robot system, and then allowing for measured results, we developed the dedicated system. The developed system can be welded by using only 3 axises in contrast with robot system using 8 axises in housing welding. In addition, we applied CMT and laser welding device to dedicated system and as a result of experiment, sound bead and excellent roundness could be obtained.

• 조명전기설비학회논문지
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• 제15권5호
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• pp.90-96
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• 2001

외란이나 시스템의 파라미터 변동 및 불확실성이 존재하는 자동화 장비의 고속 정밀제어를 위한 혼합형 퍼지제어 시스템을 제안한다. 제안된 시스템은 제어영역을 고속제어 영역과 정밀제어 영역으로 분리하였다. 먼저 퍼지 제어방식을 이용하여 고속제어를 수행하고, 오차가 설정된 범위 안에 들어오면 주파수 동기방식에 의해 제어되어 정밀제어를 수행한다. 제안된 방법을 이용하여 용접라인 및 산업용 로봇 매니플레이터, 부품조립 자동화 설비 등의 적용 예로써 서보 제어시스템에 적용하였다. 이론과 실험적인 연구가 수행되었고, 그 결과는 자동화 장비의 위치제어 성능이 개선되었음을 입증한다.

• 한국생산제조학회지
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• 제7권6호
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• pp.57-63
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• 1998

An adaptive control in the robotic GMA welding is employed to monitor information about weld characteristics and process parameters as well as to modify those parameters to hold weld quality within acceptable limits. Typical characteristics are the bead geometry, composition, microstructure, appearance, and process parameters which govern the quality of the final weld. The main objectives of this thesis are to realize the mapping characteristics of bead width through learning. After learning, the neural estimation can estimate the bead width desired form the learning mapping characteristic. The design parameters of the neural network estimator(the number of hidden layers and the number of nodes in a layer) are chosen from an estimation error analysis. A series of bead of bead-on-plate GMA welding experiments was carried out in order to verify the performance of the neural network estimator. The experimental results show that the proposed neural network estimator can predict the bead width with reasonable accuracy and guarantee the uniform weld quality.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.36-41
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• 1997

With the trend towards welding automation and robozation, mathematical models for studying the influence of various parameters on the weld bead geometry in Gas Metal Arc(GMA) welding process are required. The results of bead on plate welds deposited using the GMA welding process has enabled mathematical relationships to be developed that model the weld bead geometry. Experimental results were compared to outputs obtained using existing formulae that correlate process input variables to output parameters and subsequent modelling was performed in order to better predict the output of the GMA welding process. The aim of this work was to explain the relationships between GMA welding variables and weld bead geometry and thus, be able to predict input weld bead size. The relationships can be usefully employed for open loop process control and also for adaptive control provided that dynamic sensing of process output is performed.