• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.34-38
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• 2003

It has been used many kinds of horizontal butt-welding methods at block-to-block erection stage in shipbuilding companies. For examples, some companies use conventional FCAW process with one side or both sides groove joint welding, others use carriage with torch holder type mechanized welding method. Although lots of efforts were done until now, some problems in quality and productivity still remain in ship's hull welding. In this study, we have attempted to raise productivity and quality on horizontal position of welding with following 3 items. 1) Prepare groove condition with no root gap for making easy fit-up work. 2) Develop improved MAG (100% $CO_2$ gas shielding) welding process with solid wire for making sound root bead from one side. 3) Develop and apply quite new automatic welding carriage. The stability of new welding process was confirmed by conducting mechanical tests of weldments to verify the soundness of weldments.

• Journal of Welding and Joining
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• v.16 no.6
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• pp.104-112
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• 1998

In the previous study, the countermeasure for welding deformation of bracket tilt is through up through experimental inspection for total process including welding process. For completeness of systematic examination of parts having sensitivity on welding deformation, the comparison and feedback between the result through simulation of welding process and experimental data is needed. In other words, it is necessary to control welding deformation that construct the prediction system for welding deformation through comparison and tuning with experimental data. In the present study, the application of FEA on welding process of bracket tilt with susceptibility to deformation is made and deformation behavior through change of welding sequence is focused on. It is used to improve the exactness of deformation analysis that three dimensional analysis for moving heat source, activated and deactivated bead element, and volume heat flux etc.

• Journal of Welding and Joining
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• v.21 no.7
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• pp.42-48
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• 2003

Welding distortion is a current issue in many industrial parts, especially for heavy industry such as shipbuilding, plant industry. The welding process has many processing parameters influencing welding angular distortion such as heat input power, welding speed, gas flow rate, plate thickness and the welded material properties, etc. In this work, the conventional local minimization concept was applied to find a set of optimum welding process parameters, consisted of welding speed, plate thickness and heat input, for a minimum angular distortion. An analytic solution for welding angular distortion, which is based on laminated plate theory, was also applied to investigate and optimize the welding process parameters. The optimized process parameters and the angular distortion for various parametric conditions could be easily found by using the local minimum concept.

• Proceedings of the KWS Conference
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• 2000.04a
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• pp.310-312
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• 2000

In welding, there is much dangerous element. Workers who are exposed to working field of welding may be infected with industrial diseases. To solve these problems, many studies has been carried out. It is a good method to make welding automation in the distance and internet makes it possible. If internet is used, welding can be carried out without the limitation of time and place. On this study, welding by using internet is studied. By using internet, computer which has interface with welding machine is connected to computer in the distance and welding is carried out with the signal of computer in the distance. Basically the connection of computers is made by two program-Server and client windows program-which have functions which are needed for control of XYZ table and welding machine. Through these program, the motion of welding torch which was mounted on XYZ table, the starting and ending of welding is controlled and monitored with a camera. Also, signal-welding current and arc voltage-is measured and displayed.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.917-922
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• 2003

In this paper, a high speed rotating arc sensor for automatic fillet welding is introduced. In order to track the welding seam, The high speed rotating arc sensor is used. The welding tip of a high speed rotating arc sensor rotates about 3000 rpm using DC motor. The rotating torch is driven by gear between welding torch body and wire guide. The welding current is measured by using the current sensor and rot at ing position sensor. To realize the welding seam tracking algorithm with accuracy, a software filter algorithm using the moving average method is applied to the measured welding current in the microprocessor. The welding mobile robot with two wheels and two sliders is developed for fillet welding. The welding mobile robot can control its traveling direction and turn itself around the corner. The effectiveness is proven through the experimental results conducted with varied fillet tracking patterns.

• Journal of Welding and Joining
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• v.5 no.4
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• pp.28-35
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• 1987

The feasibility of underwater wet arc welding process is experimentally investigated by using high titanium oxide type electrodes and TMCP steel plates as base metal. It is assertained the tis process may be put to practical use. Main results are summarized as follows; (1) Sound underwater weld can be obtained by skilled welding operator, if proper welding conditions are selected. (2) In underwater wet arc welding process, the mechanical properties of HAZ are depend upon welding condition and the optimum welding condition can obtained. (3) The maximum hardness in the HAZ of TMCP steel plates is increased significantly in this welding process.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.46-50
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• 2003

The horizontal fillet joint is one of the most important weld joints in the shipbuilding industry. High-speed rotating arc welding, which can increase the leg length, is an effective way to improve the weld productivity and quality for the horizontal fillet welding. Based on the Taguchi method, the effects of welding parameters on bead characteristics - leg length, asymmetry, undercut, overlap - are investigated fur high-speed welding process. As a result, the adequate welding parameters are selected for the required leg length, symmetric bead and no undercut. Besides, considerably consistent leg length is observed for the horizontal fillet welding with gap variation up to 3mm.

• Journal of Welding and Joining
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• v.31 no.1
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• pp.26-32
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• 2013

Recently, welding technology of nonferrous metals which were difficult to implement by arc welder has become available through digitalization of arc welding machine. Among them, the welding quality improvement of aluminum welding is very noticeable. These results increase the arc stability by controlling arc current and voltage waveform precisely, and control wire feed speed by synchronizing with arc current which the feed rate of filler wire is controlled by a precise motor control of servomotor and not by a simple constant speed feeding. Not only through the hardware digitalization of arc welding machine but also through advance of software of arc welding, it became possible to implement a certain level of welding quality by a simple operation. These led to CMT welding process implementation which requires low heat input than current arc welding and highly increased the applicability of the aluminum welding.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.42-44
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• 2007

Methods of repair welding are different to production welding for welding position, welding process, welding power source, heating methods. This study investigated proper the welding process used the welding process SMAW and GTAW in the weldment of inconel filler metals. Mechanical test showed that SMAW and GTAW process had higher mechanical properties than those of material specification. Both SMAW and GTAW welding process can appy the repair welding. In comparison, GTAW welding process had more higher mechanical properties in the weldment.

• International Journal of Automotive Technology
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• v.7 no.6
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• pp.721-728
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• 2006

This paper is concerned with development of digital assembly cell. Automotive industries, try to find out new welding technologies to replace the existing spot welding which is not appropriate anymore. Because of many advantages like good accessibility, welding quality and fast welding speed, laser welding seems the most appropriate solution for automobile manufactures. To apply this technology to welding of car body, experiments must be conducted according to material, geometry and layer in welding area. Based on the data of these experiments, the laser welding process and the quality of stitches are identified. And then, the comparison between the requirements of welding and the potential of equipments allows selecting the best equipments. By using the digital manufacturing, the configurations of laser welding cell are carried out. After all, the optimal laser welding cell is chosen by the evaluation of alternative cells with technical and organizational criteria.